DESCRIPTION OF GENERA AND SPECIES- 
Omus Esch. 
0. Dejeanii, aeueo-ater, opacus, tliorace latitudine breviore, trapezoides, depresso, profunde 
intricato-rugoso, ad apicem striate, elytris punctatis subrugosis, foveisque profundis irregulariter 
impressis. Long. '7 — '8. Tab. I, Fig. 1. 
Reicbe, Annales de la Soc. Entom. France, 7,297 ; Tab. 10, Fig. 1. 
Fort Vancouver, Dr. J. G. Cooper ; Steilacoom, Dr. Suckley. 
0. californicus, ater subopacus, thorace latitudine baud breviore, trapezoides, modice 
convexo, profundissime intricato-rugoso, elytris profunde punctatis, punctis vix inaeq[ualibus. 
Long. -6. Tab. I, Fig. 3. 
Escbscboltz, Zool. Atlas, 5,4; Tab. 4, Fig. 1 : Reicbe, Ann. Ent. Soc. Fr. 7,301 ; Tab. 
10, Fig. 3. (copied) : Mann. Bull. Mosc. 1843, 182. 
San Francisco ; found by me in February, floating in pools of water ; a female was liberally 
presented to me by Mr. J. Pb. Wild. 
0. Audouinii, ater, subopacus, thorace latitudine non breviore, trapezoides, modice convexo_, 
intricato-rugoso, minus profunde in disco, margine apicali sublaevi, elytris subrugosis, 
punctatis, punctisque maioribus dispersis impressis. Long. '55 — "7. Tab. I, Fig. 2. 
Reicbe, Annales de la Soc. Entom. France, 7,297 ; Tab. 10, Fig. 2. 
Oregon^ at Fort Vancouver, Dr. Cooper. Only males were procured, but for a female, col- 
lected by the late J. K. Townsend, M.D., I am indebted to Dr. T. W. Harris. 
These three species, the only ones known, form two natural divisions, according as the 
thorax is short and depressed, (0. Dejeanii,) or oblong and moderately convex. The two 
species of the latter division resemble each other closely in form, size, and sculpture, the less 
deeply rugous thorax of 0. Audouinii at once distinguishes it ; the head of that species is also 
less deeply rugous between the eyes than in 0. californicus ; the elytra are more distinctly 
rugous, and there is an obvious difference in the size of the punctures of the elytra ; on close 
inspection, a similar character may be seen in 0. californicus, but much less distinctly. 
Pristodacttla Dej. 
P. lenis, piceo-nigra, subnitida, thorace subquadrato, postice paulo angustiore, lateribus 
rotundatis margine subreflexo, angulis posticis obtusis rotundatis, ad basin utrinque late 
foveato, elytris thorace latioribus, tenuiter striatis, bipunctatis, antennis pedibusque rufo- 
piceis ; unguibus ad basin paulo serratis. Long. '44. 
Anchomenus lenis Mann. Bull. Mosc. 1853. 
Kadjak, Russian America ; Baron Chaudoir. This species is closely allied to P. advena Lec. 
but is larger. The thorax is more narrowed behind, and the sides are less broadly reflexed. 
I was much surprised to find the ungues of this species finely serrate from the middle to the 
