974 Charles Paul Alexander 



The genus Triogma includes but three known species, the genotype 

 Triogma trisulcata (Schum.) of Europe, T. kuwanai (Alex.) of Japan, 

 and T, exculpta O. S. 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. trisulaita 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 by 

 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 Fonlinalis antipyretim Linn., to which they clung firmly 

 l)y means of two strong chitinized hooks at the caudal end of the l^ody. 

 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 most 

 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 lateral 

 rows, there is produced a copy of the ternate condition of the leaf arrange- 

 ment in FontinaUs. 



The larva of T. trisulcata (Plate LXXXIII, 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 the 

 pecuUar branched condition found in the larva. 



SUBFAMILY TipuHnac 



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 accession 

 of exotic genera and species. A study of the immature stages likewise 



I 



I 



