Gestation in Batracaians and Fishes. 47 



How this increase of size of the embryo over the original size of 

 the egg is actually obtained I have no facts to show^, but either of 

 two suppositions are probable ; it may be by absorption of mate- 

 rials from the water which surrounds it, or from the capillary 

 plexus of the pedicles, and in this case in a manner analogous to 

 that of Pipa. 



Among the Siluroid fishes of Guiana there are several species, 

 which at certain seasons of the year have their mouths and branch- 

 ial cavities filled either with eggs or young, and as is believed for 

 the purpose of incubation. My attention was first called to this 

 singular habit by the late Dr. Francis W. Cragin, formerly U. S. 

 Consul at Paramaribo, Surinam. In a letter dated August 1854, 

 he says, " the eggs you will receive are from another fish. The 

 different fishermen have repeatedly assured me, that these eggs 

 in their nearly mature state are carried in the mouths of the pa- 

 rent, till the young are relieved by the bursting of the sac. Do 

 you either know or believe this to be so, and if possible, where 

 are the eggs conceived and how do they get into the mouth ?" 



In the month of April, 185*7, on visiting the market of Para- 

 maribo, I found that this statement, which at first seemed to be 

 very improbable, was correct as to the existence of eggs in the 

 mouths of several species of fish. In a tray of fish which a negro 

 woman ofiered for sale, I found the mouths of several filled with 

 either eggs or young, and subsequently an abundance of opportu- 

 nities occurred for repeating the observation. The kinds most 

 commonly known to the colonists, especially to the negroes, are 

 Jara-hakJca^ Njinge-njinge^ Koepira^ Makrede and one or two 

 others, all belonging either to the genus Bagrus or one nearly 

 allied to it. The first two are quite common in the market and 

 I have seen many specimens of them ; for the last two I have the 

 authorithy of negro fishermen but have never seen them myself. 

 The eggs in my collection are of three diff"erent sizes, indicating 

 so many species ; one of the three having been brought to me 

 without the fish from which they were taken. 



The eggs become quite large before they leave the ovaries, and 

 -are arranged in three zones corresponding to three successive 

 broods, and probably to be discharged in three successive years ; 

 the mature eggs of a Jara-bakka eighteen inches long, measure 

 three-fourths of an inch in diameter, those of the second zone one 

 fourth ; and those of the third or very minute, about one sixteenth 

 of an inch. 



