£i8 Remarks upon the Stenmi. 



on abdomen visible, giving a silvery and fulvous ornamentation. 

 Surface of prothorax and elytra, rough. The transverse tricus- 

 pid cannse of abdomen distinct. This species is readily differ- 

 entiated from any of its congeneric associates. It is abundant at 

 Poway (elevation 700 feet), and I have not taken this form else- 

 where, although its geographical distribution is quite extensive, 

 occurring in Washington, Oregon, Nevada, and northern Lower 

 California. 



Stenus pacificus, Casey. — At first glance this species 

 closely resembles S. arizonae, but a careful examination and com- 

 parison cannot fail to readily distinguish between the two. In 

 length it varies from 2.2 mm. to 3.0 mm. Inform, moderately 

 slender. Pubescence not appreciable. Prothorax is narrower 

 than long, with anterior and posterior margins equal. Protho- 

 rax and elytra irregularly and moderately punctured. Surface 

 polished. Taken along the San Diego River m considerable 

 numbers. " I have not taken this species at Poway, yet it may oc- 

 cur there. At the present state of our knowledge of its distribu- 

 tion it appears to be pecuHar to Southern California. 



Stenus Arizona, Casey. — More robust than the 

 preceding species. Length, 3.0 to 4.2 mm. Prothorax 

 wider with margins strongly arcuate. The traces of 

 channels upon pronotum and elytra aid greatly in sepa- 

 rating this species. Abundant along the San Diego River, 

 in company with S. pacificus, and is recognized by its 

 darker color — surface not being polished. These two species 

 seem to be the characteristic species of the coast region, not hav- 

 ing found them in company with the species of the interior. Prob- 

 ably it is irregularly distributed, for it occurs in Arizona and 

 Texas. 



Areus pinguis, Casey. — I have found this species associated 

 with S. sculptilis in the Poway region. Very robust inform. 

 Contrasting strongly with its associate species by its fine, closely 

 placed, and evenly distributed punctures. In length this species 

 varies but little, being close to 4.0 mm. in all specimens mea- 

 sured. Distributed over an extensive area; according to Thos. 

 L. Casey, it occurs in British Columbia, Washington, Oregon, 

 Nevada, Colorado, besides California. 



The consideration of the local distribution of species that 

 have such an extensive range, may seem unprofitable, but as a 

 species may be very abundant in well defined localities, and en- 

 tirely absent in an adjoining region, my notes may not be without 

 value in pointing out the possibility of irregular distribiition. 



It is strange tliat during many years collecting at Poway and 

 vicinity that S. pacificus and S. arizonae should have escaped 

 my notice, while S. sculptilis and A. pinguis were abundant; and 

 that during the past season I should fail to obtain the two latter 

 species in the San Diego River region, where the former species 

 \yere plentiful. Granting the possibility o( regu/ur disindu/wn 



