740 The American Naturalist. [August, 
ZOOLOGY. 
Abnormal Duplication of Urosome in Rana catesbiana.— 
While searching the stores where aquatic supplies are sold it has been 
my fortune to obtain two tadpole monstrosities,—one from a dealer in 
Harlem, and one from a store near Cooper Union, New York city. 
The occurrence of two such specimens during the same season, each 
obtained from a different locality, sets aside the probability of either 
being the result of accident. A careful examination has led to the con- 
clusion that the malformations are congenital. As I am assured by 
Dr. John A. Ryder that nothing of the sort has been observed hitherto, 
I furnish herewith a description and sketch, as being of possible interest 
in their bearings on the morphology of monsters, 
Both are tadpoles of Rana catesbiana, far enough advanced to possess 
the posterior limbs. These, however, have very small thighs, and pre- 

sent a dwarfed appearance as compared with those of normal tadpoles 
of same size. One of the tadpoles died soon after coming into my 
possession ; the other is alive. In both the abdomen is oval and flat, 
instead of swollen and globular. This characteristic has been persist- 
ent with the tadpole now alive, although it has been furnished with 
Anacharis, Utricularia, and other food-plants, and has fed upon them - 
constantly with as much zest as is shown by ordinary tadpoles. In the 
tail of each a bifurcation takes place toward the tip, and there follows 
_a duplication of the tail above and below the axis of the body. In 
both the dorsal and ventral branches of the fin-fold occurs a series of 
muscle-plates, and a dorsal and ventral branch of the chorda corre- 
sponding to the diverging limbs of the tail-tip. The plates-extend a 
little beyond the point of bifurcation, and the notochord to the 



