NATURAL SCIENCES OP PHILADELPHIA. 415 



2. Sphaarium Barbadense, Prime. S. testa ovato-oblonga, venlricosa, 

 insequilaterali, tenui, transversira striata, intus carneo-rubra maculata, umboni- 

 bus proniinentibus, natibus acutissitnis, inclinatis, erosis ; latere antico rotun- 

 dato, postico latiore, obtuso ; epidermi ie fusco-luteolo ; dentibus cardinalibus 

 inconspicuis, lateralibus parvis, subsequalibus, antico paulo majore. 



Long. ; lat. l-5th ; diam. poll. 

 Hab. Baibadoes ; (Collect. Prime.) 



This insular species is very similar to the Sphserium Bah i ease, Spix, of 

 Brazil ; it is, however, much larger and somewhat more inflated. 



3. Spluerium Portoricense, Prime. S. testa elongato-transversa, rhom- 

 boidea, sequilaterali, tenui, cornea, trausversini fortiter striata ; valvis crassius- 

 culis, nigro irregulariter maculatis ; extremitatibus obtusa, utroque latere 

 tequaliter declivi; dentibus cardinalibus inconspicuis, lateralibus subasqualibus, 

 antico majore. 



Long. \ ; lat. l-5th ; diam. \ poll. 



Bab. Portorico ; (Collect. Swift et Prime.) 



Very similar in shape to the young of Sphserium sulcatum, Lam. This 

 species differs from the generality of West Indian and South American Sphseria 

 by its sulcations, which are quite heavy for its size. 



[Published by permission of the War Department.] 

 Descriptions of new Lower Silurian, (Primordial), Jurassic, Cretaceous, and 

 Tertiary Fossils, collected in Nebraska, by the Exploring Expedition under 

 the command of Capt. Wm, F. Kaynolds, U. S. Top. Engrs. ; with some remarks 

 on the rocks from which they were obtained. 



BY F. B. MEEK AND F. V. HAYDEN. 



The geological collections brought in by Captain Raynolds' expedition, al- 

 though, as might be expected, not containing so large a number of new species, 

 as those of some earlier explorers of the north-west, afford several very inter- 

 esting new forms, and furnish much important information in regard to the 

 geographical distribution of previously known species. Tbey also afford us 

 much valuable information respecting the extent and range of die various 

 groups of rocks, so widely distributed throughout the great area of his ex- 

 plorations. 



In the present paper we give descriptions only, of the new species contained 

 in these collections. We have, however, in course of preparation for Capt. 

 Raynolds' final Report, full illustrations, with more extended descriptions of 

 these, together with complete catalogues of all the previously known forms. 

 Before commencing these preliminary descriptions, it may not be out of place 

 to make some remarks on the formations from whtch they were obtained. This 

 we now propose to do in the order of their succession in time, commencing 

 with the oldest. 



LOWER SILURIAN (PRIMORDIAL) ROCKS. 



In March, 1858, we announced in a paper read before the Academy, that we 

 bad identified fossils of the age of the Potsdam Sandstone amongst the collec- 

 tions brought by Lieut. Warren's expeditions from the Black Hills, Nebraska, 

 Previous to that time, no organic remains of that age had been recognized either 

 from there or from the Rocky Mountain ranges farther west. The specimens 



[Note. We take pleasure in acknowledging here our renewed obligations to 

 Prof. Henry, for the free use of the extensive collection of works on geology, 

 palaeontology, &c, in the library of the Smithsonian Institution, and for other 

 facilities of great value to us in the prosecution of these investigations ] 



1861.] 



