Dr. Wyman on the Surinam Toad. 3 3BA9 
specimens of this fish, but these special efforts proved an injury,” 
&c. We may therefore confidently look forward for some new 
type of viviparous fish from San Diego. Mr. Wm. Couper of 
Toronto, Canada, writes me also that an intelligent young man 
residing in Buffalo, New York, obtained some fish taken at Black 
Rock, in which a number of young were found enclosed in a 
pouch attached to or near the back bone, resembling the parent 
in form. May this not be some Cyprinodent? Iam inclined to 
believe it, since I have of late ascertained that many of our rep- 
resentatives of that family, if not all, bring forth living young, 
though these are very small at the time of their birt 
That among our Sharks the Dogfish (Acanthias americanus, 
St.), is viviparous, has long been known. So is also Mustelus 
Canis, Mitch. But Mr. Thayer S. Abert, of the U. 8. Engineers, 
informs me that the Stingray of the coast of North Carolina also 
brings forth living young. ‘This would be, as far as I know, the 
tst example of a viviparous species in the family of Rays. 
& 
Arr. XX X1X.— Observations on the Development of the “ Suri- 
nam T'oad” (Pipa Americana); by Jerrries Wyman, M.D. 
(Presented to the Boston Society of Natural History.) 
‘Tue specimens upon which the following observations were 
made, were obtained by Dr. Francis W. Craigin, U. S. Consul, 
to whom the Society has been so frequently indebted for his gen- 
erons and munificent contributions to its cabinet, of zoological col- 
lections from South America. ‘The habits of these extraordinary 
animals during the reproductive season are well known. The 
eggs are transferred by the male to the back of the female, to 
Which they adhere, and where they are impregnated ; their pres- 
ence excites increased activity in the skin, it thickens, is gradu- 
ally built up around each egg which it at length nearly encloses 
in a well-defined pouch; this process of investment has been 
compared by J. Miller and others to the inclusion of the mam- 
miferous ovum by the deciduous membrane of the uterus. The 
Opening which is left after the pouch is formed, is at length closed 
up by an operculum, and thus the egg is shut off from all direct 
Communication with the air. 
Of the eight specimens which I have examined, two were desti- 
tute of eggs in the back, and the skin of these presented a uniform 
surface throughout covered, as is usual, with conical papilla. One 
them I ascertained by dissection to be a female, the ovaries 
being well filled with eggs. In the backs of all of the others, ova 
existed in different stages of development, the number of egg- 
Saes varying in different specimens from forty to 
