﻿410 Scientific Intelligence. 



series from his fine collection of American Blastoids;" and the 

 collections "lent for six months only," through the owner's lib- 

 erality remained "for over five years." "Mr. Wachsmuth has 

 also been kind enough to keep us informed of the progress of his 

 own researches, and in some instances these have led to the 

 abandonment or modification of views which we had previously 

 expressed." Messrs. Etheridge and Carpenter differ in some 

 points from Mr. Wachsmuth, "but it is perhaps scarcely to be 

 expected that there should be a complete concordance of opinion 

 between workers who approach the subject from altogether dif- 

 ferent sides." The authors, besides, express their indebtedness 

 to several other American workers, as also to many in Europe. 

 The British Museum collection of Blastoids "is not likely to be 

 surpassed in richness," many American species being added to 

 the British, and others from various parts of Europe. All the 

 nineteen genera are represented in it excepting the rare Pentephyl- 

 lum and JEleutherocrinus. Of the former, only one specimen (now 

 in the museum of the University of Dublin) is known. 



5. Revision of the jPalwocrinoidea, by Charles Wachsmuth 

 and Frank Springer. Second Section of Part III. (From the 

 Proc. Acad. Nat. Sci., March, 1886.) — This concluding portion of 

 Part III of Mr. Wachsmuth's important work, covers 194 pages. 

 The subject is the "Discussion of the classification and relations 

 of the Brachiate Crinoids and conclusion of the generic descrip- 

 tions." 



6. A Natural System, of Mineralogy with a Classification of 

 native Silicates; by Thomas Sterrt Hunt (reprinted from 

 Mineral Physiology and Physiography, pp. 279-401. Boston : S. 

 E. Cassino). — In this essay, which has been already presented to 

 the public in full or in abstract in several publications, Dr. Hunt 

 discusses the general question of mineral classification, and gives 

 the special application to the silicates of the views urged by him. 



The subject is too broad to be fully discussed here, but briefly 

 it may be stated that Dr. Hunt urges that in classification not 

 only the chemical composition should be taken into account but 

 the physical characters as well, and especially the specific gravity 

 and hardness. The point made by Dr. Hunt that the hardness 

 and specific gravity, and with them the degree of resistance to 

 attack by solvents, are highly significant as showing the degree 

 of atomic condensation, and hence indicating what species are 

 allied to each other, is one of importance which has been too little 

 recognized. 



His method of calculation is applied to the silicates and the 

 results taken in connection with crystallization, hardness and 

 degree of resistance to acids serve to give the basis of the classi- 

 fication. The silicates are thus divided into three sub-orders: 

 (1) those containing no alumina, (2) those with alumina and pro- 

 toxides, (3) those with alumina and without protoxides. Each 

 of these is separated into five tribes passing from the species of in- 

 ferior b ardness, lower density and easily decomposed by acid to those 



