98 



KNOWLEDGE 



[May 1, 1895. 



hundred, burst open the lids of their cells, and, after 

 stretching forth their head or a limb, make their dehut in 

 the world. Doubtless, glad to be free from her charge, 

 the mother-toad thereu^jon rubs off what remains of the 

 cells against any convenient stone or plant-stem, and 



THE PIPA. 



comes out in all the glory of a brand-new skin. During 

 the non-breeding season these toads become much flattened, 

 and seem to pass the whole of their time in water. 



The Surinam toad is, however, by no means the only 

 South American representative of its order whose nursery 

 arrangements are peculiar, a considerable number of frogs 

 and toads from the warmer regions of the New World 

 having ideas of their own as to the proper method of 

 bringing up a young family. Among these are certain 

 species nearly allied to the familiar tree-frogs of Europe, 

 but differing in that the females have a large pouch for the 

 reception of the eggs. Unlike the kangaroos and other 

 mammalian marsupials, in which the female has her 

 nursing pouch on the under side of the body, these mar- 

 supial frogs [Nototrema) have this receptacle placed on the 

 back, at the hinder end of which it forms a half-open tunnel, 

 with its aperture directed backwards, although the pouch 

 extends beneath the skin of the whole of the upper surface 

 of the body. In this capacious nursery are deposited some 

 fifteen or sixteen large eggs, which in due course develop 

 into complete little frogs, without hving tadpoles being 

 produced, although at a certain stage the large eyes and 

 long tail of a veritable tadpole are visible through the 

 clear covering of the egg. 



According to a communication recently made by Dr. 

 Goeldi, of Rio de Janeiro, to the Zoological Society, the 

 tree-frogs of the genus Hi/la, inhabiting that part of Brazil, 

 show considerable diversity in regard to nursing habits, 

 although none of them have any part of their own body 

 modified into a nursery. One species, for instance, builds 

 nests of mud on the shallow borders of pools, wherein the 

 eggs and tadpoles are protected from enemies, while 

 another kind lays its eggs in a slimy mass attached to 

 withered banana-leaves, the young remaining in this nest 

 until they have passed through the tadpole-stage. In a 

 third species, on the other hand, the larval stages are 

 hurried through before hatching, the female carrying a 

 load of eggs on her back, where they remain until 

 developed into perfect frogs. Not long since, a female of 

 this species thus loaded was exhibited alive at a meeting 

 of the Zoological Society. 



It will be observed that in all the foregoing instances 

 the female parent takes charge of the eggs, either on or 

 in her own body, or in a specially prepared nest, as soon 

 as they are laid ; but there are two genera of South 

 American frogs in which it appears that, while the eggs 

 are left to themselves, the tadpoles are carried about by 

 their mother. The members of the one genus {Dendrn- 

 hates) are tree-frogs from Surinam and Brazil, while the 

 other species is from Venezuela, and belongs to the 

 genus PJii/lloliiites. Here the tadpoles, which may be from 

 a dozen to eighteen in number, affix themselves to the 

 body of their mother by their sucking mouths, and are thus 

 carried about. In the case of one species of the genus 

 first named, it appears that this mode of locomotion 

 is only resorted to when the water is drying up and the 

 mother desires to convey her offspring to other pools ; 

 but in the other forms the attachment seems to be more 

 enduring. 



The female of Darwin's frog (Rhinoderma darwhii), from 

 Chili, has, however, " gone one better " than all her allies, 

 for not only does she get her eggs and young safely 

 carried about until they are fit to take care of themselves, 

 but she has actually shifted the onerous task of taking care 

 of them to her consort. Whereas there is nothing remark- 

 able about the structure of the female of this frog, the male 

 has a capacious pouch underlying the whole of the lower 

 surface of the body, which communicates with the exterior 

 by means of a pair of apertures opening into the mouth 

 on each side of the tongue. As soon as his partner has 

 deposited her eggs, the male frog takes them in his front 

 paws and transfers them to his mouth, whence they pass 

 into the great nursing pouch, where they remain in perfect 

 security till hatched into young frogs, which make their 

 way into the world by the same passages. 



PeciUiar as is this method of taking care of the eggs, 

 it is by no means altogether without a parallel in the 

 animal kingdom, although we have to go to the class of 

 fishes to find anything approaching a similar example. 

 Among the so-called cat-fishes {Siluridm), the males of 

 several species of the large tropical genus Arius take 

 the eggs into their mouth, whence they are transferred 

 to the capacious pharynx, where they remain until 

 hatched. It is also said that among the freshwater 

 fishes of the chromid family, the males of the typical genus 

 inhabiting the Sea of Galilee take charge of the eggs 

 in a similar manner. Indeed, among the comparatively 

 few fishes that take any care at all of their ova, the 

 charge almost invariably falls to the share of the long- 

 suffering male, whose partner, having laid the eggs, 

 appears to think that she has done quite enough In 

 family matters, and is at full liberty to enjoy herself as 

 she pleases. 



Of the two definitely known instances in which female 

 fish take care of their eggs, one occurs among the aforesaid 

 family of the cat-fishes, in the genus Aspredo, represented 

 by some half-dozen species from the Guianas. In these 

 fish, none of which exceed a foot and a half in length, the 

 large eggs are carried on the under-surface of the body of 

 the female, where they form a shield-like mass extending 

 from a short distance behind the mouth on to the pelvic 

 fins. In some respects the position of the ova recalls a 

 female freshwater crayfish in the breeding-season ; but 

 a closer resemblance exists between the fish in question 

 and the Surinam toad already described, although in one 

 case the female bears her load upon her back, and in the 

 other under her abdomen. In both instances the eggs are, 

 however, pressed into the soft spongy skin, the female 

 cat-fish effecting this operation by lying closely upon the 

 newly deposited spawn. Instead of being completely 



