Zool— Vol. I.] RITTER—DIEMYCTYLUS TOROSUS. 105 



the time of hatching, but they grow rapidly. By the third 

 day (fig. 9) the toes are already indicated. They are 

 nearly complete before the hind limbs appear, but by the 

 time the larva reaches a length of 2 cm. the hind limbs are 

 also fully developed. All the limbs are, however, much 

 slimmer and more delicate, relatively, throughout larval life 

 than they are in the adult. 



The tail-fin of the larva is very prominent at all times, 

 particularly its dorsal portion. This latter extends forward 

 on the trunk almost to the head. Its form and extent are 

 shown in fig. 7. This figure represents a larva taken 

 from Strawberry Creek late in the fall. It is somewhat 

 smaller than a majority of the specimens found at this season 

 of the year, but in other respects well illustrates the appear- 

 ance of the larva? as they are found in abundance from 

 early autumn till far into the winter. The green tinge of all 

 the parts from which black pigment is absent was slightly 

 more pronounced in the specimen here figured than is the 

 case with all individuals. 



2. Food and Feeding. — The food of the larvae consists 

 mostly of the minute organisms and decomposing organic 

 matter that collect on stones, sticks, weeds, etc., found in 

 quiet parts of the streams. Their method of feeding may 

 be easily watched, not only in aquarium specimens, but also 

 in those at home, out of doors. From the terminal posi- 

 tion of the mouth, the proneness of the body, and the 

 want of a true neck, the animal usually selects some object, 

 from the surface of which he proposes to scrape off his 

 meal, that projects sufficiently above the surface on which 

 he rests to enable him to get along without altering his 

 natural posture. Occasionally, however, when no such 

 elevated object is at hand, and the food is all scattered in a 

 thin layer over the surface on which the animal rests, he 

 exhibits in an interesting way his capability of altering his 

 usual course so as to meet the unusual conditions which he 

 finds imposed upon him. He lifts himself up on his feet, 

 " stands on his tip toes," as it may be truly said, then by 

 as short a downward flexure as possible of his head and 



