196 BERTRAM G. SMITH. 



Specimens preserved July 31 (see Fig. 3) average about 25 

 mm. long. As compared with Cryptobranchus larvae of the same 

 age after hatching, in Nectunts the general form of the body is 

 more slender, except that the yolk sac is of relatively greater 

 size. The absolute size of the Cryptobranchus larva is much 

 greater. The pigmentation in Necturus is less intense, and the 

 general appearance is that of a less advanced stage of develop- 

 ment. 



These specimens show the beginning of the dorso-lateral 

 stripes, which attain great prominence in later stages and will 

 be described in the stage in which they are most marked. 



In the larvae preserved during the latter part of August, the 

 yolk sac still persists, though its size is so reduced that the 

 abdomen is only slightly distended' by it. The lateral stripes 

 are quite distinct, though not so conspicuous as in slightly later 

 stages. The larvae average about 30 mm. in length. In Crypto- 

 branchiis larvae of the same age after hatching, the yolk sac is 

 so reduced that the abdomen is no more distended than in the 

 adult; the color is much darker than in Necturus, the form of 

 the body stouter, and the absolute size nearly twice as great. 



For a larval specimen 34 mm. long, I am indebted to Mr. 

 L. W. Harrington, formerly an assistant in the Zoological Labora- 

 tory of the University of Michigan. This specimen was obtained 

 by Mr. Harrington from fishermen in the Detroit River on 

 November 24, 1906, and was examined by me on the same day, 

 before preservation. The transparency of the ventral abdominal 

 wall enables one readily to note that the yolk has been entirely 

 absorbed. Since the coloration conforms accurately to that of 

 the Lake Monona specimens, a description of the color pattern 

 will serve for all the western larvae examined by me. 



As contrasted with the adult, the most striking feature of 

 the 34-mm. larva is the presence of a conspicuous dorso-lateral 

 longitudinal stripe, light yellow in color, on each side of the 

 body. The lateral margin of each stripe is metamerically crenate. 

 The body stripes continue unbroken and without fusion to the 

 tip of the tail; anteriorly, they are separated by a slight break 

 from similar stripes along the margin of the dorsal surface of the 

 head ; these latter are sometimes connected at their anterior ends 

 by a faint transverse bar over the tip of the snout. 



