88 Transactions of the Royal Canadian Institute 



especially in the subgenus Heteronycha, where the confusion due to 

 this variability is Ukely to be greatest. 



Key to the Canadian species of Heteronycha by the male 



genitalia. 



1. Basal lobes modified, obsolete as such, but leaving a large spine on 



one side and two approximate setae on the other, the latter some- 

 times obsolete (group pullatus) 2 



Basal lobes more or less developed, with or without an accompanying 

 spine 4 



2. Basal lobe large, with two stout spines 3 



Basal lobe small, with two stout spines pullatus Coquillett 



Basal lobe absent, no basal spines '. aurifer Coquillett 



3. A slight hairy area distal of apical lobe intrudens Dyar 



A strong hairy area proximal of apical lobe, 



diantaeus Howard, Dyar & Knab 



4. Basal lobe more or less expanded and tubercular, short-haired, with 



or without accompanying spine 5 



Basal lobe unmodified, uniformly long-haired 19 



5. Apical lobe very large, resembling the basal one, with many straight 



stout, lanceolately thickened, rather long setae (group canadensis) 



canadensis Theobald 



Apical lobe with short, recurved flattened, clinging setae 6 



Apical lobe with normally shaped setae . 9 



6. Spine of basal lobe very thick, angularly curved and of a pale appear- 



ance (group hirsuteron) . . 7 



This structure a normal curved spine, not differentiated in texture 

 from other setae, although larger (group punctor) . . 8 



7. The four species spencerii Theobald, idahoensis Theobald, hirsuteron 



Theobald, and aldrichi Dyar & K«i)ab have no marked differences 

 in the male genitalia. 



8. The four species punctor Kirby, cyclocerculus Dyar, leuconotips Dyar 



and aboriginis Dyax have no marked differences in the male geni- 

 talia. The second and third species have a stronger spine on the 

 basal lobe than the first and fourth; but the character is relative. 



9. Setae on the apical lol>e coarse and somewhat thickened, 



(group curriei) . . 10 



These setae normal, fine and slender 11 



10. Basal lobe with two stout spines on the margin . . . .curriei Coquillett 

 Basal lobe with coarse setae on the margin, no spines, 



campestris Dyar & Knab 



