NORTH AMERICAN DIPTKRA. 145 



use. Ill the Cecidoiuyidje and Psychodidre only, are a number of 

 European genera included, which it is possible may be found to 

 occur here. These are preceded by a o. 



For some valuable suggestions on the grouping of the families of 

 Nemocera, the student is referred to a preliminary paper on the 

 subject by Baron Osten-Sacken (Ent. Mo. Mag. second series, ii, 

 pp. 35-39, February, 1891). The more rational plan of the group- 

 ing of the families, as there pointed out, is adopted in this i)aper. 



A synopsis of the families of Nemocera will be found in Dr. 

 Willistoii's book above referred to. 



SYNOPSIS OF GENERA. 



I.— NEMOCERA. 

 Family CP:CIDOiAIYIDiE. 



1. — Three, or four, longitudinal® veins in the wing, in the former case the third 

 nearly always forked; in the latter case the veins always simple and 

 the fourth distinct its entire lenjrth ; wings always pubescent, no ocelli, 



first tarsal joint much shortened (Cecidomyina). 2. 



Five or more longitudinal veins in the wing, or if only four, then the fourth 

 vein forked ; wings bare or pubescent, ocelli present (except in Cecido- 



gona), first tarsal joint not shortened (Lestremina) 12. 



2. — Three longitudinal veins, the third furcate or simple '.i. 



Four longitudinal veins: cross-vein either between base and tii> of first 

 vein, or oblique and originating at base of first vein, in the former ease 

 the second longitudinal vein is straight, in the latter case sinuate. 



o .iNyiiapfa. 

 .3. — Cross-vein placed between base and tip of first longitudinal vein, frcijueiitly 



almost obsolete ...4. 



Cross vein very oblique, originating at base of first longitudinal 11. 



4. — Second longitudinal vein reaching margin at a slight or considerable dis- 

 tance before middle of tip of wing 5. 



Second vein reaching margin at or beyond the exact wing tip 8. 



a. — Third longitudinal vein simple, not furcate, first vein close to and parallel 

 with costa; hairs of wing surface scaly; antennte filiform, 1.3-jointed. 

 joints elongate, cylindrical, witii a short pubescence and without verti- 

 cils o Kpaiiiocera. 



Third longitudinal vein furcate (i. 



H. — First and second veins very closely approximated their whole length and 

 very near the costa, the second vein reaching the front border more 

 than one-third of the distance before the tip of the wing; antennai Ki- 

 te 26-jointed, joints subglobular, sessile, with short verticils 7. 



•"It must be borne in mind that the term " longitudinal," as here applied, 

 means any long vein of the wing as distinguished from a cross-vein, and thus 

 includes what is known in other families as the auxiliary vein. 



TKANS. AM. ENT. SOC. XIX. (19) JUNE, 1892. 



