The Zoological Gardens of London, always attractive, now and then acquire even additional interest by the arrival of some new inmate, or the occurrence of some rare event among those already established there. Last year the Prince of Wales's Indian collection of animals, the year before the snake-eating snake, drew extra crowds; and of late the anaconda from Brazil has rendered herself popular by bringing forth a family of snakelings; though, owing to the effects of her long journey and close imprisonment, her young ones were dead. A few years ago the largest snake in the Gardens was an African python, that deposited above one hundred eggs in a nest of moss which had been supplied to her; and as some writers about snakes had told us that the python incubates her eggs, and that only this kind exhibits any such maternal instinct, she also drew crowds of the curious.

The pythoness whose proceedings we are about to relate, having deposited her eggs, arranged them in a level mass and then coiled herself around and over them; sometimes they could be just discovered between her coils, and sometimes she covered them entirely. Heat combined with moisture are essential to the development of snakes' eggs; and in the choice of a spot in which to deposit them, the maternal instinct of the animal in a state of freedom is evident. It is generally among decaying vegetation where heat is generated, or in some moist soft herbage where the sun's rays can penetrate. To regulate the temperature in a close cage and keep the moss precisely in a condition to suit snake requirements, was by no means easy, and our pythoness seemed far from satisfied. The fact, however, was established beyond doubt, that she was hatching her eggs by the warmth of her own body.

But a most untoward disaster happened one night in the overflowing of the tank among her eggs, completely saturating them; and it was not surprising therefore, that no young pythons appeared. The enormous reptile remained coiled around and over her addled eggs for above seven weeks, after which they were taken from her. She had, and with good reason, been exceedingly irritable and even savage during this time of trial, as it was mid-winter, the season when under other circumstances she, like her companions, would have been half torpid. But her maternal affection was undeniable, and this alone was worth witnessing; since some authors would have had us believe that snakes (and particularly non-venomous ones) manifest entire indifference regarding their eggs and young. The python's eggs being, as usual, in one long string, the keeper had no little trouble in getting them from under her.

Being aquatic in their habits, and on that account requiring much water, anacondas are difficult to keep in captivity. The one lately arrived among us was no sooner released from its travelling box than it took to the tank with which its cage is furnished, and remained in it for hours and even days together. But not there, poor thing, can its swimming powers be displayed, since in close coils it completely fills it. Notwithstanding these drawbacks of London life, the Gardens can now boast of three of these valuable snakes; one of which has been a resident since 1869; while those in Paris have not survived any length of time.

One still more remarkable characteristic of the anaconda is that, like the sea-snakes (HydrophidÆ), but unlike the python, it produces its young alive. We have long been accustomed to think that only vipers produce live young—and hence their name—and that all the non-venomous snakes lay eggs. But snakes, so far as those in captivity are concerned, are continually doing what is not expected of them. Zoological Gardens afford valuable opportunities to students for acquiring knowledge of the form, size, habits, &c. of animals, and an occasional insight into their modes of life unattainable otherwise. This is especially the case regarding the Ophidians; creatures which in their native haunts are so retiring, inaccessible, and mostly nocturnal, that less has been known of them than of almost any other tribe of creatures. Regarding the subject in question, several very important zoological facts have recently been established at the Gardens, and we may add, to the surprise of the naturalist world in England. In 1862 (the same year in which the pythoness laid her hundred eggs), the then but slightly known non-venomous English snake Coronella lÆvis gave birth to a family of six live young ones in a cage in London; and several other harmless snakes in the London ophidarium have also afforded cause for surprise, not only in producing live young, but in manifesting a very decided care for them. Some New-world species have been examples of this; as, for instance, the 'garter-snake,' the 'chicken-snake,' and the 'yellow boa' of Jamaica (Chilobothrus inornatus), the latter on several occasions, and sometimes depositing eggs at the same time, but the eggs proving bad.

Mr Philip Henry Gosse, when in Jamaica nearly thirty years ago, gave much careful attention to the habits of this 'yellow boa,' a snake which sometimes attains eight or ten feet in length and is extremely active. He records a great deal of highly interesting matter concerning the chilobothrus; and, as a careful and conscientious observer, his testimony is of much value. That this snake when at liberty lays eggs, was well known, nests with eggs in them being often found. In one case a 'yellow boa' was seen issuing from a narrow passage in a bank, which when dug into was found to lead to a cavity lined with leaves and soft trash, and containing eggs. This hole had been excavated, because the dry crumbled earth was discharged at the entrance, where it lay in a heap. The passage was only just large enough to admit the snake, and the soft rubbish within must have been carried there. We cannot positively assert that the snake constructed this skilful hiding-place for herself, but if she did, she must have forced out the earth as the burrowing snakes do, or by the muscular undulations of her body; and she must have conveyed the leaves there in her mouth. Snakes do, we know, sometimes make nests by coiling themselves round and round to form a hollow. Under either circumstance maternal instinct is undeniable; and if chilobothrus merely discovered and appropriated the nest of some other creature, her intelligence is still worth recording.

We knew an instance where a snake in captivity exhibited restlessness and uneasiness, crawling about the cage as if in search of something. Those who had the care of it suspected she was with eggs, and placed some sand in the cage. This appeared to satisfy her, and the eggs were deposited. Mr Gosse had a Jamaica boa in the same condition. For a long time it manifested discomfort and restlessness, being savage and in every way objectionable, till at length it produced a family of young ones. Knowing it was the habit of this snake to incubate its eggs, Mr Gosse was greatly surprised at the event; and the startling question occurred to him, that when circumstances are unfavourable for the deposition of eggs, could a snake retain them until the young are hatched?

Mr Gosse's surmises have been entirely confirmed both by similar occurrences at the Zoological Gardens and by other writers, who in the subsequent interval have also given careful attention to the habits of Ophidians, and have produced valuable scientific works on the subject. It is now an ascertained fact that not chilobothrus only but several other oviparous species may at pleasure be rendered viviparous by retarding the deposition of their eggs when circumstances are unfavourable for them! In fact we find that we must almost discard those old distinctions of oviparous, viviparous, and ovoviviparous; which German authors tell us are not founded on any other ground than a greater or less development of the fetus in the egg at the time of laying; or on the nature of the exterior covering of the egg; which is thicker and leathery in those which take some time in hatching, and slighter and membranous in those which are hatched either before or on deposition.

In serpents the eggs differ from those of birds by undergoing a sort of incubation from the very first, so that whenever examined, the embryo more or less advanced will be found. In the case of the pythoness of 1862, an egg was examined on the fifteenth day of incubation, and found to contain a living embryo; a noteworthy fact, as the python incubates for fifty-six days before hatching her eggs. Observations with the eggs of chilobothrus are attended by the same results—namely the fetus in a certain stage of development is discovered whenever a gravid snake is killed and examined. The young ones of the boa in the London collection were perfectly developed and active, climbing all over their cage as soon as they saw daylight. One family consisted of thirty-three; another of eight; and another of fourteen. The activity and daring of the snakelings were amazing, affording ample proof of their perfect development. They were always on the defensive, shewing fight on the slightest molestation. When the keeper put his hand into the nest among them they seized upon it and held on so tightly with their teeth, that on raising his hand they hung to it, wriggling and undulating like a waving golden tassel. I ventured to take up one of these aggressive little reptiles, but could scarcely hold it, from its energetic wrigglings and contortions. It constricted my fingers tightly enough to prove its singular instincts, and bit me savagely with its sharp little teeth; but my glove being on, I permitted this, glad of so good an opportunity for making personal observations.

It was said of the python that notwithstanding her care and vigilance so long as she was incubating, when her snakelings were born she took no notice of them. This may not always be the case. Vipers we know are extremely watchful over their young; other snakes are often seen accompanied by a young brood; and in the Jamaica boa maternal affection is exhibited in no slight degree. A lady visiting the Gardens compassionated one of these young families on the gravelly floor of their cage, and brought a quantity of cotton wool, which was placed in one corner. She was rewarded by seeing the luxury fully appreciated, mother and little ones all huddling into it immediately.

That these non-venomous snakes thus produce their young under abnormal conditions is further confirmed by the varying size and appearance of the offspring, and by their being more or less enveloped in the shell-covering. Some are born quite coiled in the ruptured shell, others with portions of it clinging about them, and others again entirely free. Sometimes they are, as it were, imbedded in the coriaceous covering. This was conspicuously the case with the anaconda's progeny, but her young ones had every appearance of having been a long while dead. The first of the six was freer from the shell than the others, and about a foot and a half in length.

Snake-life is altogether marvellous. The power which some snake mothers possess of retarding the deposition of their eggs, and we have reason to believe, sometimes even the young when circumstances are unpropitious for her to produce them, seems to us specially curious. Chilobothrus is known to have had both eggs and a living brood. So has Coronella lÆvis. Of the latter, some German ophiologists state that it is 'always viviparous;' others 'occasionally' so. In her native Hampshire woods she has been seen with a young brood about her; but there seems no satisfactory evidence of any eggs having been found. Time and careful notings only can substantiate this and many other singular facts regarding these 'wise' and 'subtle' creatures, hitherto surrounded by prejudice and but little studied. We, not well versed in Ophidian biographies, might have expected the anaconda to lay eggs because her cousin the pythoness did so; and we might have also speculated upon her incubating them, as the python did. But she has produced a perfectly developed though dead family of six, instead; a circumstance of so much interest to naturalists, that the loss of the young ones is to be regretted though not wondered at. Captured from her native lagoons, and shut out from the light of day in a box just large enough to contain her, this 'good swimmer' arrives alive; thus proving her amazing powers of endurance; but she has had no fitting place in which to deposit her young, and they died unborn. Still it is a noteworthy fact in the annals of zoology. At first, from the result of observation, the incubation of the python was 'suspected;' then it became confirmed; and the birth of young coronellas also. From this it is evident that we cease to declare that only vipers produce live young; or, according to the original signification of the word, a boa, a coronella, and several other non-venomous snakes would be 'vipers!'

Again, it is remarkable that these peculiarities of reproduction are not confined to particular families and genera; because some coronellas lay eggs, some incubate them, and others bring forth a live brood. So also, while some of the BoaidÆ lay eggs, the anaconda is completely viviparous.

We would venture to urge upon those lovers of nature who dwell 'remote from towns' the value of careful observation and a noting down of what appears unusual, even of the habits of the much persecuted snake.

C. H.