6 



OfflUS, Esch. 

 (Omos— Cruel.) 



Black, more or 'ess opaque (1 submetallic), wingless, head nearly square, eyes 

 small, palpi of equal length, the labial with the hrst joint very short, third lorjg; an- 

 tenna? inserted in front under a prolongation before the eyes; mandibles very long, 

 acute, at the right side with two teeth, on the left with three ; thorax somewhat 

 flattened ; elytra convex ; legs stout, short. 



$ .—Has the three joints of anterior tarsi dilated (more inwards) and densely 

 spongy beneath; last ventral segment deeply emarginate at the middle. 



2 . — Has the last ventral segment oval at tip and entire. 



The larva, (tab. 1, fig. 14,) described by Dr. Horn, 1. c, p. 31, is yellowish-white; 

 head piceous; prothorax scute pale castaneous; has eight eyes, two pairs large, two 

 pairs small; antennas with the first three joints equal, fourth shorter; maxillary palpi 

 with joints one and three equal, second shorter. Length in normal flexed position, 

 20 mm. 



This genus is also nocturnal, found on the Pacific Slope from 

 Vancouver Island to Monterey Co., California. They hide under 

 pieces of wood and may easily be baited by placing finely chopped 

 meat near small pieces of board, under which they can be found the 

 next day. 



Horn, Trans. Am. Ent. Soc, v. 284, (on sexual characters) ; Trans. Am. Ent. Soc, vii, 31, 

 (description of the larva of Omus Dejeanii); Hy. Edwards, Psyche, i, 73, (on the localities and 

 habits of Omus). 



TABLE OF OMUS. 



I. — Lateral margin of the thorax obliterated posteriorly, not attaining the basal 

 margin. 

 Surface black. 



Thoracic margin distinctly reflexed. 



Elytra foveolate and opaque Dejeaiiii. 



Elytra simply punctate and shining Edwartlsii. 



Thoracic margin extremely feeble. 



Elytra rather irregularly punctate Audouinii. 



Surface bronzed. 



Elytra broadest near the apex, form nearly parallel.. .Sllbmetallicus. 

 IL — Lateral margin of the thorax attaining the basal margin. 

 Elytra moderately coarsely punctured. 



Thorax nearly square lloiii i i . 



Thorax narrowed behind, rugulose califoriliciis. 



Thorax narrowed behind, comparatively smooth. 



Eorm robust, labrum bisinuate seqiloiai'Uiu. 



Form slender, labrum nearly truncate L.ecoiltei. 



Entire surface smooth, impunctured lap vis. 



This table has been prepared from notes furnished by Dr. Horn. 



1. O. Dejeanii, Reiche, (tab. 1, fig. 2.)— Our largest species, easily dis- 

 tinguished by the deep irregular foveas of the elytra. Length 15 — 20 mm. 



Habitat. — Vancouver Island, Northern California, Oregon and 

 Montana. April to July. 



Reiche, Ann. Pr., 1833, p. 299, tab. 10, fig. 1 ; Thorns. Mon., p. 15, tab. 3, fig. 4 ; Leconta, 

 P. E. R. Exp., 47 Par., p. 27, fig.; H. Edwards, Psyche, i, p. 73. 



