Coleopterological Notices. 379 



the island by an appreciable interval, the island being thus isolated, 

 rising rapidly like a stupendous peak from a great depth, we should 

 have to assume an enormous subsidence, but of course this alone 

 would not invalidate the theory. It may be possible also that as 

 the intermediate region subsided, there was a gradual and counter 

 elevation of the land seaward forming the apex of the peninsula. 



The subsidence of the peninsula probably continued through the 

 Pliocene, but it was not until the early Quaternary that the islands 

 near the coast became isolated.* It is only natural to assume, there- 

 fore, that which we know to be true, that the fauna of these islands 

 should be less modified than that of Guadalupe, although remaining 

 closely allied to it. The ancestral type of Coniontis lata has, in 

 Guadalupe, become the densely pubescent genus Coelotaxis, while 

 upon the mainland it seems to have totally disappeared, there being 

 no species at present known which at all resembles G. lata or its 

 variety insidatHs. 



A thorough exploration of these islands by a scientific entomo- 

 logist would be fruitful in many interesting results bearing upon 

 their geological history, especially would' this be the case with the 

 epigeal species which are not readily transportable by winds and 

 ocean currents. This is perhaps the greatest desideratum in our 

 knowledge of the nearctic fauna. 



C. opaca Horn. — Trans. Am. Phil. Soc, XIV, p. 296. — Oblong-oval, 

 strongly convex ; sides snbparallel ; elytra sometimes slightly inflated behind; 

 surface almost smooth, dull and finely alutaceous. Head finely, somewhat 

 densely punctate ; antennae somewhat slender. Prothorax rather short, nearly 

 three-fourths wider than long, the apex fully two-thirds as wide as the base, 

 the latter almost transverse, broadly, feebly sinuate laterally, the angles sub- 

 acute and scarcely projecting posteriorly beyond the median lobe ; sides broadly 

 rounded anteriorly, parallel and nearly straight in basal half; disk finely but 

 deeply, distinctly and very densely punctured toward the sides, very minutely 

 and more sparsely so toward the middle ; lateral margin not reflexed, finely 

 beaded. Elytra very distinctly more than twice as long as the prothorax, 

 very finely punctate, the punctures finer and much feebler and sparser than 

 those toward the sides of the pronotum. Abdomen polished, very finely, 

 sparsely punctate. Ze^s slender. Length 8.3-9.8 mm. ; width 4.0— 4.6 mm. 



California (Owen's Valley) ; Nevada (Reno). 

 This species is peculiar to the arid eastern slopes and foot hills 

 of the Sierras, and those specimens from other regions, which have 



1 See an interesting paper bearing upon this subject, by Prof. Joseph 

 LeConte, Bull. Cal. Acad. Sci., II, p. 515. 



