198 



BERTRAM G. SMITH. 



By dissection it was found that the yolk sac, though reduced 

 almost to the form of a digestive tube, still contained a small 

 amount of yolk. Assuming that this larva had been hatched 

 about 8-10 weeks, we find a similar condition of the yolk sac 

 in Cryptobranchus larvae of the same age after hatching. 



FIG. 6. Living larva of Neclurus, 35 mm. long. (X J.) 



This specimen differs from the western larvae in that the dorso- 

 lateral stripes unite in the median line at the base of the tail, 

 to be continued as a single stripe along the dorsal edge of the 

 tail (see Fig. 5). Since this peculiarity is present in all the 

 fourteen larvae that I have examined from the eastern habitat, 

 it would appear to be a constant difference between the eastern 



FIG. 7. Larva of Necturus, 55 mm. long, photographed after preservation in 

 ormalin. Nearly actual size. 



and western forms. Otherwise the color and color pattern of 

 both eastern and western larvae are the same. 



The larger specimens may be described as follows: A 42-mm. 

 larva taken on August 29, 1907, differs morphologically from 

 the 35- mm - larva in its slightly greater yolk content; evidently 

 it is younger, though of greater size. A specimen 55 mm. long 



