378 Coleoplerological Notices. 



peculiar to them ; and it is also a fact that the proportion of endemic 

 species and the relative divergence of type become more pronounced 

 as we proceed southward, until in Guadalupe the endemicity becomes 

 one of the most remarkable of the faunal characteristics. 1 



A correlation of these facts seems to indicate that the islands off 

 the coast at one time formed a continuous peninsula, trending 

 almost directly north and south, joining the continent by a broad 

 base between Pt. Concepcion and Cape Yincente, 2 and tapering to 

 a point at Guadalupe. The fact that the submarine contours exhibit 

 ;i series of salients in the 500, 1000, 1500 and 2000 fathom curves, 

 extending in the general direction of Guadalupe, gives greater 

 probability to this assumption. 



At that time, which was probably at least as early as the begin- 

 ning of the Pliocene, there was a free intermingling of the conti- 

 nental species characterizing this epoch. Shortly thereafter the 

 peninsula began to subside, interrupting this communication, and, 

 as the islands were successively separated, the quota of individuals 

 remaining upon them gradually diverged under the isolated and 

 special environmental conditions by which they became surrounded ; 

 or, in short, have become specifically distinct. 



Guadalupe being the first land detached should display the most 

 marked divergence in its productions, although by this hypothesis 

 the essential features should remain as purely Californian as those 

 of the other islands, — facts which have long been well known. It 

 may be objected, however, that as the salient of the 2000-fathom 

 continental contour is separated from the corresponding contour of 



1 Out of 296 species of plants collected by the eminent Californian botanist 

 Mr. E. L. Greene, on the Island of Santa Cruz, 48 are peculiar to the Santa 

 Barbara group, and 28 are peculiar to Santa Cruz alone. In Guadalupe out 

 of 145 known species of plants, 24 are strictly endemic. Except the birds, 

 plants, however, form perhaps the least reliable criterion for the estimation of 

 relative endemicity, as the strongly vitalized and often comparatively inde- 

 structible seeds are so apt to be successfully introduced by currents, winds 

 and migratory birds. The real faunistic isolation of these islands will be 

 much more clearly demonstrated by the wingless epigeal species of Coleoptera, 

 and of these there is not a single species at present known from Guadalupe 

 which is not strictly peculiar to the island. 



2 To one passing along the coast of Santa Barbara Co. and viewing the very 

 bold and precipitous slopes of the Santa Inez Mountains, the desire to liken 

 them — in connection with the present subsidence theory, — to the escarpment 

 of a great fault, is almost irresistible. 



