EMBRYOLOGY OF CRYPTOBRANCHUS 531 



white. In the two-year-old larva the general color effect is not 

 so dark; the larva is taking on the variegated color pattern of 

 the post-larval and adult stages. 



In the month-old larva, shedding of the cuticle was observed 

 for the first time. From this time on, the water of the aquarium 

 becomes almost cloudy with detached portions of epidermis. 



Soon after the hatching period, cilia disappear from the general 

 surface of the body, but persist on the gills where a strong eddying 

 current of water is produced. The gills remain ciliated until 

 at least six months after the hatching period ; at this point obser- 

 vations were necessarily discontinued. 



As early as five months after hatching and frequently there- 

 after, larvae have been observed to come to the surface for aii 

 and to give up large bubbles of air from the mouth, indicating 

 that the lungs are functional. 



During the first year of larval life, the ventral portions of the 

 three gill arches bearing the external gills are expanded into 

 leaf-like plates, partly covered by the opercular lateral portions 

 of the gular fold. At this time there are three gill openings. 

 Toward the end of the first year the median portion of the gular 

 fold disappears, but the lateral portion extends as a small opercu- 

 lar fold above the root of the anterior external gill. During 

 the second summer the opercular fold extends dorsally far enough 

 to cover the bases of all three external gills. With the loss of 

 the external gills the opercular flap persists and partly roofs 

 over a shallow cavity containing the leaf-like plates previously 

 mentioned. 



C. Post-larval stages 



Sexual maturity is attained with a length of at least 30 cm. 

 for the male, and 35 cm. for the female. During August, speci- 

 mens 14 to 20 cm. in length have been very rarely taken, while 

 specimens measuring from 20 cm. upwards are very plentiful ; 

 this suggests that the young ordinarily reach a length of at least 

 20 cm. at the end of the third year, and that they do not ordinarily 

 become sexually mature until the end of the fourth year. 



