211 



tending to apex of second abdominal segment ; legs, to or nearly to 

 apex of third. Abdominal segments more or less distinctly sub- 

 divided by transverse incisions; dorsum of all segments or of the 

 apical 2 with long thorn-like processes ; lateral margins with short 

 thorn-like protuberances. 



Imago. — See key to subfamilies. 



HABITS OF IvARVAE 



The larvae of this subfamily feed upon living plants, and are, as 

 far as I know, the only species of Tipuloidea that have this food-habit. 

 They also differ from all other Tipuloidea except Dicranomyia 

 in being green. It is very difficult to detect them upon their food 

 plants, which consist of living mosses, or, in the case of Cylindrotoma, 

 of Viola, Stellaria, and Anemone. Phalacrocera feeds upon sub- 

 merged aquatic mosses. The larvae are very sluggish. 



HABITS OF IMAGINES 



The fhes are rather sluggish, and may be swept from plants on 

 which the larvae have fed or from those along the margins of streams 

 or ponds. 



Keys to Genera 



LARVAE 



1. Thoracic and abdominal processes long and slender, the posterior 



submedian pair on each abdominal segment furcate near bases; 



aquatic or semiaquatic species (PL XXXIII, Fig. 1) 



Pliala croc era. 



— Thoracic and abdominal processes short and leaf-like, not furcate 



near bases, at most with short protuberances 2 



2. Dorsal processes simple Cylindrotoma. 



— Dorsal processes with short protuberances anteriorly 3 



3. Some of the dorsal processes with 4 short protuberances on their 



anterior surface Triogma. 



— None of the dorsal processes with more than 2 protuberances on 



their anterior surface Liogma. 



PUPAE 



1. Only the apical 2 abdominal segments with long, rather slender 

 protuberances (PI. XXXIII, Fig. 4) Plialacrocera. 



— All abdominal segments with long, slender protuberances. .Liogma. 



