182 CHARLES W. LENG. 



Death, the palpi, pleurse, coxje, flanks of thorax, legs and sides of 

 abdomen are thickly clothed with white hair. 



Since the above was written Prof. Wickham has informed me of 

 the occurrence at Nogales, Ariz,, of C. mexicana King., Jahrb., p. 

 31, 1834. This species resembles 16 punctata, and the original de 

 scriptiou is as follows : y: j- /lu* '***(> C^v^t- 



"Subtus cupren, abdoniiue rufo-testaceo, supra fusco-senea, elytris puncto ante 

 apicem, lunula humerali fasciaque transversa sinuata media late interruptis 

 albis." 



EXPLANATION OF PLATES. 



PLATE I. 



California may be divided roughly into three parts, viz. : the desert regions of 

 the southeast, the broad central valley of the Sacramento and San Joaquin 

 Rivers, and the mountain ranges of the coast and the eastern portion. In the 

 first two divisions the species of Omus do not live; they are confined to the 

 mountains and foot hills. 



The mountain ranges of California north of Santa Barbara County may be 

 arranged in three groups, viz. : 1st, the confused cross ranges of Del Norte, Siski- 

 you, Humboldt, Trinity and Shasta Counties; 2nd, the Coast Range, having a 

 general altitude of 2000 to 6000 feet, and extending the entire length of the 

 State ; 3rd, the Sierra Nevada, having a general elevation of 5000 to 8000 feet, 

 with occasional ridges of 10,000 feet and individual peaks that exceed 14,000 feet, 

 and extending from the northern boundary to Tulare County. 



In the first group Omus Audouini is found, and it occurs also to the northward 

 in Oregon, Washington and Vancouver. In other words. Northern California is 

 the southern limit of this species. Close to its territory is that of Omus ambiguus, 

 a very closely related species. 



In the second group of mountains, the Coast Range, is the territory inhabited 

 by Omits caiifornicns and Omiis Lecontei, the first being confined to the lower foot 

 iiills about San Francisco, the second inhabiting the southern Coast Range of 

 Monterey, San Benito, San Luis Obispo and Santa Barbara Counties, and proba- 

 bly, the western part of Kern County. In the northern part of Monterey 

 County, where the two territories may overlap, occur the doubtful forms, which 

 have some of the characters of both species, and there Omus elongatus should be 

 sought. 



In the third group, the Sierra Nevada, the greater elevation of the ridges inter- 

 poses a greater obstacle to the free mingling of individuals of Omus, and each 

 valley is liable to harbor a race which has become sufficiently differentiated for 

 recognition. The species occurring in this region are therefore more numerous 

 and, at the same time, less widely separated from each other. The most north, 

 ern form, snbmetallicas seems the closest to Audouini; and as the habitat becomes 

 more southern the divergence seems to increase. In the broadest view, the 



