EMBRYOLOGY OF CRYPTOBRANCHUS 67 



B. GENERAL CHARACTERISTICS 



1. Size 



Out of the many hundreds of adults captured, the largest male 

 (September 3, '08) measured 60 cm. (23| inches) long and weighed 

 2| pounds. The largest female captured (September 3, '09) 

 weighed exactly 3 pounds. The latter animal unfortunately 

 escaped from the aquarium in which it was confined and was not 

 measured; probably it was no longer than the longest male, but 

 heavier because distended with eggs. Professor McGregor 

 reports a specimen 25 inches long, taken from the Scioto River. 



The great majority of specimens captured by me were much 

 smaller; specimens of about 30 to 50 cm. were most frequently 

 taken. The smallest sexually mature male measured 30 cm.; 

 the smallest mature female 35 cm. 



2. Form 



As compared with the young, the adult is more flattened dorso- 

 ventrally — an adaptation to life in shallow crevices. The head 

 particularly shows this flattening: it is wedge-shaped as viewed 

 from the side, a form which enables the animal to force its soft 

 body into very shallow crevices. 



Moreover, as compared with the young, the adult is distin- 

 guished by a general looseness and wrinkling of the skin at the 

 sides of the body, forming broad lateral horizontal folds; and by 

 similar flaps of skin on the posterior sides of the limbs. During 

 locomotion these folds and flaps undulate in the water, contrib- 

 uting to the uncouth appearance of the animal. 



3. Coloration 



Young sexually mature individuals vary little in color or color 

 pattern. The ground color is dull brown, with conspicuous black 

 spots and less conspicuous yellow spots scattered over the dorsal 

 and lateral surfaces. Both kinds of spots are irregular in size and 

 form. The coloration of young adults is practically that of 



JOURNAL OF MORPHOLOGY, VOL. 23, NO. 1 



