178 W.P. Blake on the Grooving and Polishing of Rocks. 
and is not known in Oriental seas, except in New Zealand and 
Tasmania. So also the important genus Homarus; besides 
Hyas, Herbstia, Leptopodia, Atelecyclus, Munida, and Grimo- 
thea. 'The genus Homarus has one species on the coast of the 
United States, one on the coast of Europe, and one at Table 
facts, where ascertained, show to be well characterized. In some 
cases, a further subdivision may be desirable, and when so, the 
subordinate divisions may be called Districts. In each Kingdom, 
the Provinces of each zone together may constitute a Sub-king- 
dom, as the Torrid Subkingdom, Temperate Subkingdom, &c. 
Arr. XVIL.—On the Grooving and Polishing of hard Rocks 
and Minerals by dry Sand ; by Witutam_P. Buaxe, 
Tue phenomena about to be described were observed in the 
Pass of San Bernardino, (California) in 1838.* This Pass is one 
_ of the principal breaks through the southern prolongation of the 
Sierra Nevada, and connects the Pacific slope with the broad 
is 2808 feet above the Pacific, and the width of the gap at that 
point is about two miles: from this the ground slopes each way 
very gradually, the grade or descent on the east, for about 28 
miles, being on an average, 69 feet per mile. 
On this eastern declivity of the Pass—the side turned toward 
the Desert—the granite and associate rocks which form the sharp 
peak of San Gorgonio extend down to the valley of the Pass in 
a succession of sharp ridges, which being devoid of soil and of 
vegetation, stand out in bold and rugged outlines against the clear 
unclouded sky of that desert region. 
It was on these projecting spurs of San Gorgonio that the phe- 
nomena of grooving were seen. ‘The whole surface of the gral- 
ite, over broad spaces, was cut into long and perfectly parallel 
grooves and little furrows, and every portion of it was beaut 
fully smoothed, and though very uneven, had a fine polish. For 
a moment it was impossible to realize the cause of all this abra 
* A brief notice of these phenomena is given in the writer's Preliminary Geol 
gical Report, ace ying the Report of Lieut. R. S. Williamson, of a Reconnol® 
sance in Ualifornia, House Doc. 129, p.27. Washington, 1855. ; 
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