NEW SPECIES OF PALiEOZOIC FOSSILS. 583 

 BKACHIOPODA. 



LINGULA PINNAFORMIS. (N. S.) 

 (Tab. I. r,, figs. 4, G, 8.) 



Specific character. — Shell shaped much like a Pinna; moderately convex ; expanded, and running 

 to a point at the beak, which iu the dorsal valve is long, conical, and slender, curved towards the beak 

 of the ventral valve, which it overhangs and embraces as with a deltidium. Surface marked with fine 

 concentric strife ; when exfoliated, longitudinal stria; can also be detected towards the circumference of 

 the shell. Length, $ of an inch ; greatest width, T 7 g of an inch. 



This fossil is abundant in the siliceo-calcareous layers near the base of member h of F. 1, at the Falls 

 of the St. Croix, Minnesota. 



LINGULA AMPLA. (N. S.) 

 (Tab. Lb, fig. 5.) 



Specific character. — This species has a greater circumference and superficial area than any of the 

 others hitherto discovered in F. 1. Shell nearly oval, rather flat; beak blunt, and not projecting beyond 

 the general contour of the shell, and formed more after the manner of the beaks of Terebratulee. A few 

 faint concentric striae. Length, ]l of an inch; width, J g of an inch. 



This species occurs in the Lingula and Obolus grits, member c, near Mountain Island, at the Dalles of 

 the St. Croix, and elsewhere in Wisconsin. 



ORBICULA PRIMA. (N. S.) 



(Tab. I. b, figs. 17 and 19, and top figures on Tab. 4.) 



Specific character. — Shell obliquely depressed, conical; circumference nearly circular or slightly quad- 

 rangular; concentric and somewhat subquadrangular strife. y* g to T 5 g of an inch in diameter. 

 Associated with the preceding species at the Falls of St. Croix, Minnesota. 



ATRYPA COMIS. (N. S.) 

 (Tab. III. a, fig. 4.) 



Specific character. — One of the valves of this Atrypa being broken and distorted, it only admits of a 

 partial description. Shell subspheroidal ; umbos but slightly prominent ; surface smooth. Diameter 

 about one inch. From the Davenport Limestone of the Upper llapids of the Mississippi of Devonian 

 date. 



CIIONETES GRANULIFERA. (N. S.) 

 (Tab. V., fig. 12.) 



Specific character. — When first obtained, this Chonctes was referred to the species C. rariolata ; a 

 closer inspection, however, induces the belief that it is a new species, since it differs from that species in 

 the following characters : 



The ribs, or rather strife, are finer, and are not separated by other finer strife, visible to a moderate 

 magnifying power, nor are there any pits (" fossettes") to be observed on them. The surface of the 

 concave, ventral valve is provided, like the C. variolata, with pustules, but they are fewer iu number and 

 less regularly disposed than shown on PI. XX., fig. 2 a, of De Komich's work on " Productus and C'honetes." 



The form of the medial tooth of the ventral valve, and the anatomy of its visceral portion, are diffe- 

 rent, as may be seen by reference to Tab. V., fig. 12 i. 



From the carboniferous limestone, near the mouth of Keg Creek. 



