“J. Wyman on some unusual modes of Gestation. 9 
‘To those species enumerated above where the eggs become 
_ more or less mtimately connected with the body of the parent 
after they are laid ma) Pax added the Aspredos and some species 
of Bagrus, from G 
Aspredo levis (Cav. pe Val.), the “Trompetti” of ane t oleate 
is asus fifteen inches in length, and belongs to a remarkable 
genus of Siluroid fishes, which, in addition to several pentianitien 
of anatomical structure, are remarkable for carrying the eggs an 
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 
general y, and in consequence these are known among the colo- 
nists as Ningré fist or ‘‘ nigger fish.” A general account of the 
internal stuckare of Aspredo, is given the Hist. Nat. des 
Poissons, by Cuvier and Valenciennes, T. x 30. 
In deconting the organs of reproduction, Fe Ren aanits says: 
‘the ovaries are small and contain very large eggs, which leads 
to the belief that this fish is viviparous.” In those specimens 
which I have dissected the eggs when a eee are not remarkable 
for their very great size, peng from 0°09 to 0°11 inch in diameter, 
even after the commencement of the development of pe ee tus, 
and when the egg has Rea increased in size, aries 
are ee an inch and a half long and capil Bee | from 
eac oth er, 
urth ibes certa ages to the under 
side of the eae are certain fied TPeaiduals | in each 
species (of Aspredo) are remarkable for singular appendages on 
under side of the thorax and abdomen, and which, after the 
few observations which I have been able to make appear to indi- 
eate a certain state of the female. I have not seen them in the 
males and the females do not have them at all times. . They first 
appear as pores on the under and naked surface of the trunk ; 
and these enlarge and swell into tubercles, which ribeon ult 
dilated into a small cupule.” 
“Tt was in this state that Bloch saw them in an individual 
with six cirrhi, and, taking them for specific characters, named 
the fish Platystacus cotylophorus. But I have seen the same ap- 
pendages in three species. Artedi, in the text of Seba, had 
affords oa oD cee ye vascular surface by means of which an interchange takes Pike 
between the foetus and the parent. The vitelline circulation in shade, fe 
resp bias circulation. The allantois of the Marsupials bp 
rudimentary condition, and does not form a connection with the Citak Thus the 
yascular relation of the foetus of some of the sharks, as Carcharias, with the parent 
* Cuvier and Valenciennes, Hist. Nat. des Poissons. T. xy, p. 430. 
SECOND SERIES, Vor. XXVII, No. 79,—JAN., 1859. 
9 . 
