128 PROCEEDINGS OF THE ACADEMY OP 



laterali, tumidula ; striis regularibus distantibus ; epidermide flavescente in- 

 duta ; valvis solidiusculis, intus albis, umbonibus prominentibus, erosis, 

 cardine crasso, tridentato. 



Long. 11 ; lat. 10 ; diam. 6 mill. 



Hab. '(Collect. Prime.) 



14. Corbicula v i o 1 a c e a Prime. C. testa ovato-transversa, subaequilate- 

 rali, obliqua, extremitatibus aequaliter obtusa, transversim irregulariter 

 striata ; epidermide squalide virescente vestita ; umbonibus magnis, obliquis, 

 erosis, intus profunde violacea ; cardine angusto tridentato. 



Long. 15 ; lat. 13 ; diam. 8 mill. 

 Hab. ? (Collect. Jay et Prime.) 



15. Corbicula Agrensis Prime. 



Cyrena Agrensis Kurr., in litt. 



C. testa ovato-transversa, aequilaterali, laevigata, depressiuscula, extremi- 

 tatibus rotundata ; epidermide viridi-olivacea induta ; sulcis regularibus, dis- 

 tantibus ; intus pallide violacea ; umbonibus tumidis, erosis ; cardine angusto, 

 dentibus cardinalibus crassis, lateralibus aequalibus, tenuiter serrulatis. 



Long. 9 ; lat. 8 ; diam. 5 mill. 



Hub. Agra, India. (Collect. Prime.) 



16. Corbicula inaequilateralis Prime. C. testa ovato transversa, 

 depressiuscula, tenui, inaequilaterali ; extremitatibus rotundata ; umbonibus 

 prominentibus, approximatis, antice obliquatis, violaceo subradiatis ; sulcis 

 regularibus, intus pallide violacea ; epidermide pallide virescente induta ; car- 

 dine angusto ; dentibus cardinalibus crassis, lateralibus inaequalibus. 



Long. 16 ; lat. 12 ; diam. 8 mill. 

 Hab. Africa. (Collect. Prime.) 



17. Sphaerium Vermontana Prime. S. testa ovato-trigona, tumida, 

 inaequilaterali,, striis regularibus, epidermide viridi-fiavescente vestita ; um- 

 bonibus tumidis ; cardine arcuato ; dentibus lateralibus crassis. , 



Long. 11 ; lat. 10 ; diam. 7 mill. 

 Hab. Vermont, N. America. (Collect. Prime.) 



This species, though somewhat allied to Sph. striatinum Lam., is much 

 more inequilateral. 



Descriptions of new Palaeozoic Fossils from Illinois and Iowa. 



BY F. B. MEEK AND A. H. WORTHEN, 



Of the Illinois State Geological Survey. 



ECHINODERMATA. 



CRINOIDEA. 

 Genus PLATYCRINUS, Miller, 1821. 



Platycrinus Oweni. Body rather large, cup-shaped, or sub-hemispherical 

 below the summit of the first radials, rounded on the under side, height about 

 two-thirds the breadth. Base saucer-shaped, or nearly four times as wide as 

 high, pentagonal in outline, the sides being nearly straight or slightly concave, 

 sutures anchylosed; columnar facet large, its breadth equalling about half that 

 of the base, concave, margined by a slightly raised somewhat undulated rim, 

 and perforated by a large central opening. First radial plates large, sub- 

 quadrangular in general outline, but having the superior lateral angles trun- 

 cated for the reception of the anal and interradial pieces, widening a little 

 from the base upwards ; facet for the reception of the second radial pieces 



[June, 



