292 ANNUAL OF SCIENTIFIC DISCOVERY. 



two shells have been identified with American fossils ; one, the Tur- 

 binellus irifundUmlum, occurs in the upper Eocene of South Carolina; 

 and the other, Chama arcinella, in the Miocene formation of the Uni- 

 ted States. The fish all belong to species found fossil in Malta, and in 

 the older tertiaries of America. These green shales, which are about 

 six hundred feet in thickness, are covered by a few feet of coarse con- 

 glomerate, which is overlaid by a tufaceous limestone, about three 

 hundred feet thick, and containing many fossils. The most abundant 

 of these are corals, of which there are five species, belonging to three 

 genera, all of which have living representatives in the West Indian 

 seas. Not one, however, can be identified with any living species. 

 The mollusca of the tufaceous limestone are eight in number, four of 

 which also occur in the green shales above mentioned. One only, 

 Pleurotoma Virgo, is believed to be still living. The groups of fossils 

 which appear to have the closest resemblance to that of the green 

 shales are, in North America, the Upper Eocene beds of Vicksburg, 

 described by Mr. Conrad ; and, in Europe, the Maltese tertiaries. 



ON THE DEPOSITION OF THE CHALK. 



At a meeting of the Boston Natural History Society, January, 

 Prof. Rogers read the following memorandum on the probable depth 

 of the ocean of the European chalk deposits : 



Various geologists, and among them Professor Edward Forbes, in 

 Lis excellent and learned Paleontology on the British Isles, in John- 

 ston's Physical Atlas, have suggested that the ocean of the chalk de- 

 posit of Europe was a deep one ; and in evidence of this, Prof. Forbes 

 cites the striking relationship existing to deep sea forms of the Eng- 

 lish chalk corals and brachiopods ; adding, that the peculiar Echino- 

 derms (Holaster, Galerites, Anarchy tes, Cidaris, Brissus and Gonias- 

 ter) favor this notion, as also the presence of numerous foraminiferse. 



1 beg leave to present a difficulty in the way of this conclusion. 

 Several of these genera of Echinoderms, as Anarchytes, Cidaris, c., 

 occur in the green sand deposit of New Jersey referable by any 

 fossil test to the age of the green sand and chalk of Europe ; and this 

 American stratum was unquestionably the sediment of quite shallow 

 littoral waters. That they must have had a trivial depth is proved by 

 the circumstance that they repose in almost horizontal stratification, 

 at a level of not more than from 100 to 200 feet lower than the gene- 

 ral surface of the hills and upland region to the N. W. of the margin 

 of the zone they occupy at their outcrop. It is obvious that a depres- 

 sion of the cretaceous region, such as would cover the present deposits 

 with a deep sea, would have likewise overspread the low gneissic 

 hills to the N. W. of the Delaware, which present no traces of having 

 ever been submerged during the cretaceous in any secondary period." 



Mr. Ayres remarked that of those genera of Echinoderms which Mr. 

 Forbes regarded as deep sea genera, two or three are found in North 

 America, in water not 200 feet deep. Terebratula, which has been 

 generally regarded as only an inhabitant of very deep water, and 



