974 CHARLES PavuL ALEXANDER 
The genus Triogma includes but three known species, the genotype 
Triogma trisulcata (Schum.) of Europe, 7. kuwanai (Alex.) of Japan, 
and T. exculpta O. 8S. of the eastern United States. The last-named 
species is very rare and its habits are entirely unknown. 
The first reference*to the immature stages of T. trisulcata is by Steinmann 
(1907-08), who discusses the larva as that of an unknown species of 
Phalacrocera. The true identity of this insect was made known b 
Miiller (1908-09). Steinmann found the larvae at Sackingen at the end 
of April, fourteen days after the melting of the snow. They were found 
in mountain streams, attached to and living among the stems of the 
aquatic moss Fontinalis antipyretica Linn., to which they clung firmly 
by means of two strong chitinized hooks at the caudal end of the body. 
The larva resembles to a startling degree the moss on which it lives. 
Along the dorsal surface are two rows of leaflike appendages, each of the 
abdominal segments having three such appendages, of which the mos 
anterior one is the shortest and the posterior one is the longest. The 
anterior appendage is untoothed, the others have as many as four teeth 
on the anterior face. The pleural region likewise bears a row of leaflike 
structures, while the ventral surface shows a double row of small, knoblike 
leaflets. Thru the strong accentuation of the dorsal and the two latera 
rows, there is produced a copy of the ternate condition of the leaf arrang 
ment in Fontinalis. 
The larva of T. trisulcata (Plate LX XXIII, 452) is of a light green color 
marked with darker blotches, and measures 19 millimeters in length. The 
longest body appendage is 1.5 millimeters in length. Miiller found larvae 
and also pupae. The pupa is characterized by the possession of somewhat 
similar appendages to those of the larva, the dorsal row showing thd 
peculiar branched condition found in the larva. 
The subfamily Tipulinae comprises a remarkably homogeneous assem: | 
blage of usually large species. It is made up of a relatively few but in | 
some cases very extensive genera, which are found thruout the world] 
Efforts have been made in the past to maintain three tribes — the 
Dolichopezini, the Ctenophorini, and the Tipulini. It has become increas 
ingly difficult, however, to define these groups on the constant accessio | 
of exotic genera and species. A study of the immature stages likewis¢ 
SUBFAMILY Tipulinae 
