Batrachians and Fishes. 7175 



know them under any other circumstances. The existence of yelk- 

 cells in the intestine shows that for a period at least they may have 

 from these a supply of nutriment ; but after this is exhausted — and it 

 appeared to be nearly so in those which I have dissected — how do they 

 obtain their food ? In the absence of limbs adapted to terrestrial loco- 

 motion can they leave the body of the parent ? And if they cannot, do 

 they, as in the case of Pipa, and probably in Notodelphys, depend 

 upon a secretion from her ? 



Among fishes, as far as at present known, the external conditions 

 under which the eggs are developed are more varied than in any other 

 class of vertebrates. There are scarcely any known conditions of the 

 higher classes to which there are not analogies, at least in the class of 

 fishes. Besides the ordinary mode of depositing eggs upon the bottoms 

 some of the Salmonidae, like the turtles, bury their eggs ; the lampreys 

 {Petromyzou), ihe breams (Pomotis), the hassars {Callicthys), the stickle- 

 backs {Gasterosteus), &c., build more or less complete nests. 



Among some of the pipe fishes {SyngnaUiidie) the eggs, and subse- , 

 quently the young, are carried in a pouch analagous to that of the 

 opossums and other marsupial animals ; and among some of the 

 sharks there is a vitelline placenta analogous to the allantoidan, one 

 of the Mammalia. 



To those species enumerated above, where the eggs become more 

 or less intimately connected with the body of the parent after they 

 are laid, may be added the Aspredos, and some species of Bagrus, 

 from Guiana. 



Aspredo laevis {Cuv. aud Fa/.), the "Trompetti" of the colonists, is 

 about fifteen inches in length, and belongs to a remarkable genus of 

 Siluroid fishes, which, in addition to several peculiarities of anatomi- 

 cal structure, are remarkable for carrying the eggs and young attached 

 to the under surface of the body. These fishes are very abundant in 

 the waters of the Surinam, where they are taken in the nets with 

 other kinds. They are not used as articles of food, except by the 

 negroes, who have a fancy for Siluroids generally, and in conse- 

 quence these are known among the colonists as Ningre fisi, or 

 "nigger fish." A general account of the internal structure of Aspredo 

 is given in the ' Histoire Naturelle des Poissons,' by Cuvier and Valen- 

 cienne. 



In the month of June the eggs are found adhering to the under 

 side of the body, to the ventral and pectoral fins, and extend as far 

 forward as the under lip, and as far backwards as the middle of the 

 tail. In some, however, the distribution is much more limited. I 



