37 



through environment, or approach to sterility in some fe- 

 males. As I have taken specimens over 2\ inches in 

 length, with stout bodies, and retaining gills, and from same 

 ponds procured adults of much smaller size, it would seem 

 that the habits of development and periods of growth are 

 widely different. Any examination of the peculiarities of 

 this animal must consider the absence of the miniatus form 

 near tide water and the finding of adults on dry land, 

 although able to live in water. 



Prof. Gage says he has never seen the cast-off skin rolled 

 up and swallowed by the aquatic form. I have seen them 

 seize small pieces of the exuvium partly detached from the 

 hind legs and swallow it. 



Up to 1 89 1 no observation is known to have been made 

 of the duplication of the tail above and below the axis of 

 the body. During that summer I discovered two such spe- 

 cimens of tadpoles of Rana catesbiana which were described 

 and illustrated in the American Naturalist of August, 1891. 

 At present I have an adult D. viridescens in which a similar 

 duplication exists. The body is fully developed, being 

 over three-fourths of an inch in diameter and over two 

 inches in length. The tail is thick and short, — about an 

 inch long, — with continuous fin-fold, but prominent vertical 

 duplication of muscle plates and apparently of chordae, 

 although dissection would be necessary to prove the ex- 

 istence of the latter. As the specimens already mentioned 

 were larval and were preserved as such, it is probable that 

 such duplication has not hitherto been observed in an adult. 



Since writing above, I have received a larval Diemyctylus 

 of such unusual size that I have thought it well to describe it. 



Color above, uniformly brown. Yellow beneath, with 

 brighter ventral line. No ocellated spots. Entire upper and 

 under surface thickly punctate with black dots. Sharply 

 keeled from occiput to end of tail. Length 3^ inches; stout. 



Branchiae extenal, fully fimbriated, with no indication of 

 atrophy. The animal shows signs of distress if removed 

 from water. 



