30 Notices of Memoirs — T. H. Holland — 



rocks, has just now forwarded for examination a very interesting 

 collection of the remains of Bithyrocaris ^ from excavations in the 

 shales of the Millstone-grit series at Eccup, Yorkshire, 



§ II. In the " Proc. United States National Museum," vol, xix 

 (1897), Mr. C. Schuchart has a paper " On the Fossil Phyllopod 

 Genera Dipeltis [Packard emend.^ and Protocaris." The latter was 

 noticed in our Eeport to the Association for 1889, p. 64, and in our 

 Ninth Report (for 1891), p. 300. The original genus Dipeltis was 

 established by A. S. Packard, in the " Memoirs of the National 

 Academy of Sciences," vol. iii (1885), Mem. xvi, p. 145, pi. v, 

 figs. 2, 2a, as one of the Carboniferous Xiphosura of North America. 

 In the December number of " Natural Science," 1897 (vol. xi, 

 p. 401, figs. 2-5), in his paper on "Fossil Apodidge," Mr. H. M. 

 Bernard follows Mr. Schuchart in regarding the Dipeltis, as defined 

 by the latter, as a Phyllopodous Apus-larva. Mr. C. J. Gahan, 

 however, in "Natural Science," Januar}', 1898, pp. 42-44, points 

 out that it is really a larval form of the Blattarian insect Etoblattina, 

 described and figured by H. Woodward in the Geological 

 Magazine, 1887, p. 433, PI. XII. 



§ III. With reference to the Bohemian EstTierits mentioned at 

 p. 4 of our Eeport for 1893 (Tenth, 1894), Dr. Anton Fritsch has 

 infoi'med us that thej'' were named by him in the " Sitzungsb. k. 

 bohm. Gesellsch. Wissen.," 1894 : No. 1 being PJstheria triangularis, 

 Fr. ; No. 2, E. cyenea, Fr. ; No. 3 [and No. 4?], U. palceoniscorum, 

 Fr. ; and No, 5, E. calcarea. 



IV. — The Comparative Actions of SuBAJiRiAL and Submarine 

 Agents in Eock Decomposition. By Thomas H. Holland, 

 A.E.C.S., F.G.S., Geological Survey of India.^ 



TN Europe nearly all crystalline and igneous rocks of any 

 considerable age show signs of hydrous decomposition, which 

 by the microscope can generally be traced far beyond the limits of 

 the very evident superficial crust of weathered products : in some 

 cases, like the peridotites, the changes due to hydration, even in 

 rocks of Tertiary age, have resulted in a practically complete 

 alteration of the original constituents. In working over various 

 parts of Peninsular India, the writer has been struck b}^ an almost 

 constant absence of any but the most superficial traces of hydration, 

 even in minerals like olivine and nepheline, which are so noticeably 

 susceptible to the action of water. As in all tropical and moist 

 climates, however, a complete and rapid superficial decomposition is 

 shown by most of the rocks, and in some areas they are found to be 

 changed into a ferruginous clay, which, though forty or fifty feet 

 thick, is found to retain the characteristic macroscopic structures of 

 the original rocks. In some districts, where the atmosphere is 

 always warm, and during the monsoon season highly charged 

 with moisture without great precipitation of rain, the rocks are 



^ For which we propose a new species, D. insignis. 



2 Eead before Section C (Geolog-y), British Association, Bristol, 1898. 



