513 



referred to, ranked them as subgenera, but in his recent papers on the 

 group he has raised them to generic rank. It is the opinion of the 

 writer that our knowledge of the early stages and adult habits of this 

 group is entirely too meager for an understanding of existing generic 

 relations, and pending further life-history data the current subdivi- 

 sions are here accepted without either admitting or questioning their 

 validity. The characters used are rather obscure, difificult to appre- 

 ciate, and in other families would not generally be considered as of 

 primary importance ; but owing to the scarcity of outstanding struc- 

 tural characters it is essential that importance should be given to even 

 minute details provided they are constant in form. In the use of char- 

 acters for subgeneric separation the present writer confines himself to 

 those which are possessed by both sexes in common, or to such male 

 characters as are in coordination with characters possessed by the 

 other sex. The erection of a genus for the reception of males with 

 certain hypopygial or antennal characters without reference to the 

 characters by means of which females may be assigned to the genus 

 is not conducive to a better understanding of the group, nor does it 

 facilitate the work of identification but, rather, retards it, and should 

 be avoided. The writer hopes at some future time to deal with the 

 species of this group in a more detailed manner. 



Key to Subgenera (After Kieffer) 



1. Eyes with short hairs 2 



— Eyes bare 3 



2. Palpi with 4 joints Tricliodadius (p. 514) 



— Palpi with 3 joints Biplocladius* 



3. Pul villi large Psectrocladius (p. 519) 



— Pul villi absent 4 



4. Empodium indistinct Orthocladius (p. 521) 



— Empodium filiform 5 



5. Palpi with 4 joints Dactylocladius (p. 526) 



— Palpi with 3 joints Trissocladius* 



The members of the genus Cricotopus have hairs on the eyes, and 

 are rather arbitrarily separated from those of Tricliodadius by the 

 color of the legs. Kieffer, in I9i3t» based his separation of the two 

 genera on the presence or absence of pulvilli. Cricotopus is stated to 

 have large pulvilli, but in the species before me it is very difficult to 

 see them, and unless under high magnification with good light they are 



*Unknown to me. 



tRec. Ind. Mus., A'ol. 9, p. 123. 



