BEMBIDIIN/E 17 



is rather abruptly defined and conspicuous. Dull black specimens 

 also occur among those normally having metalic lustre in the lit- 

 orale group, and I particularly note two of lorquini among a good 

 series also taken at Duncan's Mills. It is difficult to understand 

 the reason for this pronounced melanism, which has the nature of 

 dimorphism, as there do not seem to be any intermediates. 



The species allied to honest um, placed in this group by Mr. Hay- 

 ward, will be found further on in the ustulatum group. 



Group III nitidum 



9 



Subgenus Eudromus Kirby 



Pogonidhtni Gangl. 



Our species described under the names nitidum by Kirby and 

 obliqulum* (Bemb. aptuni) by LeConte, are congeneric in every way 

 with the European laticolle Duft. ; the above subgeneric name was 

 proposed for nitidum, and so Pogonidium Gangl., must be regarded 

 as a synonym. In laticolle the sides of the prothorax are much 

 more sinuate at base and the elytral striae laterad somewhat more 

 evident, but in all other characters, including habitus, there is com- 

 plete concordance; laticolle has a metallic-blue coloration, while our 

 species are polished black; the strial punctures are very fine in both 

 and the dorsal punctures are on the third interval and very small. 

 The mentum tooth is rather short and wide and broadly sinuato- 

 truncate at apex. The head is notably small, in marked contrast 

 with the preceding groups. Obliqulum is considered a slight vari- 

 ety of nitidum by Horn and Hayw r ard, but the tw r o are fully distinct 

 and in no way very closely allied. Of nitidum I obtained three 

 specimens at Duluth and have a large series of obliqulum from var- 

 ious parts of California; there is no marked variability to be ob- 

 served and I strongly doubt that any true intermediates exist; if 

 so they are specifically distinct from either. 



* The spelling "obliqiiulum" was employed by LeConte for this species, as well as 

 some others, such as Teretrius obi., and this spelling is generally repeated in the lists; 

 it seems to the writer, however, that the second u is superfluous and that the form 

 obliqulum would be better. 



T. L. Casey, Mem. Col. VIII, Oct. 1918. 



