Balrachians and Fishes. 7173 



Unusual Modes of Gestation in Batrachians and Fishes. 



Among Batrachians the circumstances under which the young are 

 developed, though less varied than in some of the other classes of verte- 

 brates, still present a considerable range. By most species the eggs 

 are deposited in the water, either upon aquatic plants or on the bot- 

 toms ; by others, as in Salamandra erythronota, they are laid in damp 

 places under logs or stones ; with some the evolution of the embryo 

 commences a short time previous to the laying of the egg, and is com- 

 pleted subsequently, while there are species which are wholly vivi- 

 parous. The most remarkable deviations from the ordinary modes 

 are to be found in those instances in which the eggs, after being laid, 

 are again brought into a more or less intimate relation with the parent, 

 as in the " swamp toads " (Pipa Americana) of Guiana, where each 

 ovum is developed in a sac by itself on the back of the female, in 

 Notodelphys of Venezuela, where all the eggs are lodged in one large 

 sac also on the back, analogous to the pouch of the marsupials, 

 and in Alytes, the " obstetric toad " of Europe, where the eggs are 

 wound in strings around the legs of the male, who takes care of them 

 until they hatch. 



The species, the habits of which are noticed below, and which, in 

 so far as I have been able to learn, have not attracted the attention of 

 naturalists, adds another to the series just mentioned, though the 

 relation of the fcetus to the parent becomes less intimate than in any 

 of the preceding cases. 



Hylodes lineatus, Dum. and Bib., is very common in Dutch Guiana, 

 and its peculiar habits are well known to the colonists. The first 

 specimen with young which came to my notice had been preserved in 

 alcohol, and was presented to me by Mr. G. O. Wacker, residing at 

 Otembo, on the Para Creek, Surinam, and had been captured at some 

 distance from the water. The young, ten or twelve in number, though 

 separated from the parent, he assured me, when found were attached 

 to the back. In the month of May, 1857, during an excursion to the 

 country inhabited by the Bush negroes, above Sara Creek on the 

 upper Surinam River, 1 had an opportunity for the first time of seeing 

 these animals carrying their young. The grass and bushes were quite 

 wet from a recent fall of rain, and this seemed the inducement that 

 led them from their hiding places, for when the ground vvas dry none 

 had been seen. They were very quick in their movements, and when 



