422 Coleopterological Notices, V. 



California (Siskiyou Co.). 



This species is allied to ater and megarthroides, differing greatly 

 from the former in its still smaller size, narrower form, more dis- 

 tinct setie and much finer, denser sculpture, and from the latter in 

 coloration and in its more parallel and less anteriorly attenuate 

 form. In pacificuin, ater and probably generally throughout the 

 genus, there is a transverse row of longer erect setae near the 

 middle of each abdominal segment and the minute erect setae of 

 the elytral punctures are replaced at wide intervals by longer setae ; 

 the small and ordinary elytral setae in ater are very much more 

 minute than in pacificuin and can scarcely be discerned under com- 

 paratively high power. The type appears to be a female. 



Oi megarthroides I have many examples of all degrees of color 

 and immaturity. The measurements given by Fauvel seem to be 

 a little too great, my series of thirty-one specimens, taken in nume- 

 rous localities from Los Angeles to Yictoria, give as extremes of 

 length 1.75-2.6 mm. ; megarthroides appears to be extremely 

 closely allied to humile Makl. 



O. lacustre n. sp. — Narrow, elongate, subparallel, feebly convex, pol- 

 ished, rufo-testaceous throughout, the head and abdomen, especially toward 

 apex, rather darker and more plceous ; pubescence consisting of extremely 

 minute suberect scarcely visible setse, denser and much longer on the aluta- 

 ceous under surface of the abdomen. Head distinctly but not greatly nar- 

 rower than the prothorax, wider than long, triangular, with the epistoma 

 truncate and one-half as wide as the base ; eyes moderate, at one-half their 

 length from the base ; the tempera parallel, nearly sti-aight and almost as 

 prominent a^the eye; base truncate, the constriction extending transversely 

 and deeply across the dorsal surface ; ocelli separated by two-fifths the entire 

 width, on the edge of the constriction ; occiput not impressed before them ; 

 surface finely, rather closely but unevenly punctate, very feebly biimpressed 

 between the antennje, the latter pale, yery short, one-third longer than the 

 width of the head, subcylindrical, scarcely visibly incrassate, outer joints 

 transverse ; last joint of the maxillary palpi subbulbose toward base, gradu- 

 ally finely attenuate and feebly arcuate thence to the apex, nearly three times 

 as long as the third but scarcely as thick. Prothorax one-half wider than 

 long, widest before the middle ; sides broadly rounded, becoming rather more 

 convergent and straighter toward base; disk finely, rather closely punctate, 

 without anastomosing impressed lines, with two elongate subobsolete median 

 impressions and another scarcely visible between them near the apex. Elytra 

 but just visibly wider than the prothorax, quadrate, as long as the head 

 and prothorax, scarcely as long as wide, finely, very densely punctate and 

 obsoletely, longitudinally substriolate. Abdomen a little narrower and rather 

 longer than the elyti-a, subparallel ; border rather wide. Legs short ; poste- 



