GG 



PALjBONTOLOOT op NEW-YORK. 



451. 2. SPIRIFER {n. sp.). 



Pl. XXII. Fig. 2. 



Dorsal valve thiee-fouitlis as high as wide (compressed in the specimen described), rounded 

 at the extremities ; hinge-line short ; mesial sinus broad and shallow, not well defined, marked 

 by four ribs ; surface of the shell on each side the mesial sinus marked by twelve or more 

 ribs; ribs rounded or flattened, smooth or w'ith slight indications of longitudinal striae. 



The specimen is a single dorsal valve, which has been somewhat distorted by pressure ; but 

 the characters remaining seem to be sufficient to distinguish it from any known species in 

 this part pf the series. The extremities of the hinge-line are remarkably contracted. There ap- 

 pear to be some remains of longitudinal strice upon the surface of the ribs, as in D. niagaren^s ; 

 but that species is readily distinguished by having fewer ribs on the sides, and none in the me- 

 sial sinus. 



Position and locality. In the thin calcareous layers associated with the lower shale near 

 Sodus, Wayne county. 



452. 3. SPIRIFER RADIATUS. 



Pl. XXII. Fig. 3a-t. 



Spirifer lineatus. Sowerby (not Martin), Min. Conchology, pag. 151, tab. 493, fjg. 1 & 2. 

 S. radiatus. Sowerby, Sil. System, pag. 637, pl. 12, fig. 6 ; and pag. 638, pl. 21, fig. 5. 



Ddthyria radiatus. Geol. Rep. 4th Dist. N. York, 1843, p. 105, fig. 2 a, 6. 



Shell variable in form, subtriangular, rotund or subglobose ; valves almost equally convex, 

 the beak of the dorsal valve more or less extended, and curving over the ventral valve ; hinge- 

 line often less than the width of the shell, the extremities being rounded ; surface marked by 

 fine close radiating stria? ; mesial elevation and depression moderate, marked by the strise as 

 other parts of the shell ; dorsal area more or less exposed, and giving a very variable appearance 

 to the shell ; foramen narrow and long, often partially or entirely closed by a callosity ; inte- 

 rior plates of the dorsal valve near together, and extending downwards within the limits of the 

 mesial depression. 



This shell has occasioned so much doubt and perplexity among several amateurs, that I have 

 given in this place figures of its principal forms, and the variations to which they are subject. 

 The beaks of the two valves are often so closely approximated that no area is visible ; and at 

 the same time the extremities are rounded and contracted, so that the shell has more the ap- 

 pearance of an Atrypa than a Spirifer. In others the extremely wide dorsal area gives one 

 the impression that there is a species having this constant character, and quite distinct from 

 those with the moderate area and rounded extremities. After examining numerous specimens, 

 I am able to see no distinction, and the numerous intermediate forms unite the whole as a 

 single species. 



