Geology and Mineralogy . 319 



observe a surprising analogous circumstance. We have known 

 for some time that the Cenomanian strata of Mexico and Texas 

 represent a mediterranean facies, but the Senonian also represents 

 an analogous facies in Mexico (and Jamaica ?). In northern 

 United States, that is to say, in New Jersey, is found, according 

 to Credner, a facies of the Senonian which corresponds closely 

 with that of the northern part of Europe ; on the. other hand, the 

 fauna described represents in this work a facies which corre- 

 sponds fairly well with that of Gosau, in the way that the facies 

 of the Senonian of northern America corresponds with that of 

 the north of Europe." c. s. 



17. An almost complete specimen of Strenuella strenua (Bill- 

 ings) ; addendum by H. W. Shimer (communicated). — A peculiar 

 oversight prevented the author of the article in the March num- 

 ber (p. 199) from seeing Shaler and Foerste's figures of this spe- 

 cies under the name of Pty chop aria mucronatus S. and F. in 

 Bull. Mus. Comp. Zool., xvi, pi. 2. They here give four figures, — 

 a thorax of 13 segments minus the pygidium, attached to a par- 

 tial, unidentifiable cephalon, two cephala without free cheeks, and 

 a free cheek. The thorax shows a median row of mucronate 

 tubercles. The free cheek figured as belonging to this species 

 has a much longer genal spine than the present specimen. The 

 latter (xxiii, p. 200), which shows very closely the relationship of 

 the different parts, has no tubercles upon the first and last seg- 

 ments, which alone preserve this portion unbroken. The relation 

 of the plural to the axial segments is similar in each. It thus 

 appears that S. strenua is quite variable in the shape of the free 

 cheeks and in the ornamentation of the axis. 



1 8. Black Sands of the Pacific Slope in 1905 ; by David T. 

 Day and R. H. Richards. Pp. 84. Advance chapter from 

 Mineral Resources of the United States for 1905. The call sent 

 out in March, 1905, by the U. S. Geological Survey to placer 

 miners at different points in this country, alluded to in an earlier 

 number of this Journal (xx, 410), has now resulted in the bring- 

 ing together of a large amount of material, the discussion of 

 which is given very thoroughly in this pamphlet. The exami- 

 nation of the samples received has shown that the following min- 

 erals, in the order named, are most commonly found in these 

 sands : Magnetite, gold, ilmenite, garnet, zircon, hematite, chrom- 

 ite, platinum, iridosmium, mercury, amalgam, olivine, and iron 

 silicates, pyrite, monazite, copper, cinnabar, cassiterite, and corun- 

 dum. Other heavy minerals are only exceptionally found. 



With respect to the occurrence of platinum, information with 

 regard to which was the primary object of the undertaking, the 

 following statement is made ; " Platinum was found in 120 local- 

 ities. The investigation showed that the largest field of plati- 

 num, and the most profitable field for commercial exploitation, 

 is comprised in Coos, Jackson, Curry, and Josephine counties, 

 Oregon, and in Del Norte, Siskiyou, Humboldt, and Trinity coun- 

 ties, California. Outside of this region platinum is also found to 



