STROMBECK HILS-CONGLOMERATE ECHINODERMS. 13 



were almost invariably found either in close connexion with, or often 

 imbedded in, the plates of mica. It was likewise remarked, that the 

 quartz, when in contact with large plates of mica, became of a smoke- 

 brown colour, which otherwise it was never found to possess ; also 

 that the felspar often became of a darker colour, and was then gene- 

 rally accompanied by some rarer mineral. 



Various observations seem to prove that both the felspar and the 

 mica have crystallized before the quartz ; the mica- plates apparently 

 floating about in a solution from which the quartz had subsequently 

 crystallized. 



Beyond the abstract here given, the remainder or greater part of 

 the communication treats of the minerals separately, with regard to 

 locality, mode of occurrence, crystalline character, and chemical con- 

 stitution ; and is of such length that reference on these points must 

 be made to the paper itself. It may be mentioned, however, that 

 four new minerals, called Alvite, Tyrite, Urdite, and Bragite, are an- 

 nounced ; the chemical examination of which shows the presence of 

 very rare chemical elements ; also that three of them contain a 

 considerable amount of water, notwithstanding their being situated 

 in granite of igneous origin. [D. F.] 



On the EcHiNODERMATA of the Hils-Conglomerate in North- 

 western Germany. By A. von Strombeck. 



[Leonhard u. Bronn's N. Jahrbuch f. Min. u. s. w. 1854, p. 641-656.] 



Among the characteristic fossils of the Hils-conglomerate in the 

 Northern Hartz and in Hilse, the Echinoidea are some of the most 

 important, partly on account of peculiarity of form, and partly from 

 their abundance ; and as yet they have not received sufficient atten- 

 tion. Hence it happens that geologists, though well acquainted 

 with the rich variety of the Neocomian Echinodermata of Switzerland 

 and France, remain still in doubt with regard to the place of the Hils- 

 conglomerate (although indeed A. Roemer, in his work on the Chalk- 

 formation, has already referred it to its true geological horizon). 

 For this reason M. v. Strombeck was induced to determine with 

 precision the species from the Hils-conglomerate ; more especially as 

 he possessed for comparison some good suites of Neocomian fossils 

 from Neuchatel, Ste. Croix (Jura Vaudoise), Mont Saleve near 

 Geneva, Censeau (Dep. Jura), Escragnoles (Var), Castellane (Basses 

 Alpes), &c., with which he was favoured by geologists living near 

 those localities ; and further, since M. Desor, one of the best autho- 

 rities on the Echinoidea, had lately revised the Hils-conglomerate 

 species in M. v. Strombeck's collection, some of which were repre- 

 sented by fifty and more specimens. The determinations may there- 

 fore be considered as correct. 



At the same time M. von Strombeck in this paper furnishes some 



