55 



locomotion of the body. Kill specimens by dropping into 

 boiling water. After the specimens have straightened out 

 and stiffened, requiring about a minute (death is almost in- 

 stantaneous) remove to thirty per cent, alcohol. After two 

 or three hours remove to fifty per cent, alcohol, and after 

 three hours into seventy per cent, alcohol. After twelve to 

 twenty-four hours remove the specimens to eighty-five per 

 cent, alcohol, in which keep them. 



Structure of body. — (Verify the following statements if 

 Holorusia is used : if another Tipulid is used compare con- 

 ditions with those here described.) The body is composed 

 of thirteen segments (exclusive of the head). Retracted into 

 the (apparently) first and second segments is the head^ with 

 strongly chitinized skull. At the anterior end of the head, 

 usually projecting slightly, are the short, cylindrical, unseg- 

 mented antennce and the strongly chitinized mouth-parts. 

 (The mouth-parts can be better examined after the larva 

 has been dissected and the retracted head wholly exposed.) 



There are no legs or tracheal gills (as there are in the larva 

 of Corydalis). The hindmost body-segment bears terminally 

 on a fiat surface two large spiracles (breathing openings, see 

 p. 74, Comstock's Manual), surrounded by six backward pro- 

 jecting flexible lobes. On the ventral surface of this seg- 

 ment is the anal opening of the alimentary canal on an eleva- 

 tion bearing four large and two smaller flexible processes. 

 The segments of the hinder half of the body have each a 

 median transverse constriction ; those of the anterior half 

 are difficult to distinguish from one another but it is as- 

 sumed that each pair of the lateral groups of setce of which 

 five pairs may be noted, represents a segment. The ab- 

 sence of all paired appendages back of the head is to be 

 noted. 



Make a drawing of the whole oody of the larva from a lat- 

 eral aspect. 



