Zool.— Vol. I.] HITTER— DIEMYCTYLUS TOROSUS. 103 



IV.— The Larva. 



1. General Description. — A larva, twice its natural 

 size, three days after its escape from the gelatin, is shown 

 by fig. 9. 



The length of this individual was 13 mm. at the time of 

 making the drawing, and this was a good average specimen. 

 The young larvas are quite transparent excepting for the 

 black pigment which they contain, and the considerable 

 amount of yoke which persists on the ventral side of the 

 body for a considerable time after hatching. 



The pigment is mostly disposed in two well defined bands 

 which extend along the dorsum from a little behind the eyes 

 to the extreme tip of the tail. These bands are, corre- 

 sponding with the greater width of the head than any other 

 portion of the body, considerably farther apart in this region 

 than elsewhere. The tail and the hinder portion of the body 

 are so thin that when the animal is looked down upon from 

 the dorsal side the two pigment bands are scarcely distin- 

 guishable from each other. The bands are sometimes per- 

 ceptibly heavier in their posterior than in their anterior 

 halves. At the time of hatching there is usually scarcely a 

 trace of pigment excepting in the bands. It is but a short 

 time, however, before scattered pigment spots begin to ap- 

 pear all over the dorsum of the head, dorsum and sides of 

 the body, on the tail fin, particularly the dorsal lobe of it, 

 and on the limbs and feet, as soon as these are formed. 

 Microscopical examination shows that generally each of 

 these spots is at the beginning a single, large, much branched 

 cell, closely resembling those found in many young fishes. 

 At first, and for a considerable period, very little or no dif- 

 fuse pigment is visible. Figs. 6, 7, and 8 illustrate these 

 points. 



The gills, three in number on each side, are well devel- 

 oped at the time of hatching, though the secondary filaments 

 are few in number as compared with those of the full-grown 

 larva. At first the three gills are of nearly equal length, 

 the ventral, or anterior one, being slightly shorter than either 



