New Species of Crinoidea and other Fossils. 221 



This is a distinct and well marked species, not easily to be mis- 

 taken for any other now known to me. Its nearest analogue is 0. 

 crenistria of the Hamilton group ; but the striae are sharper, with 

 the apex more appressed, and somewhat ditferentl}^ situated. 



Formation and locality. In rocks of the Hudson-river group, 

 Oxford, Ohio. From Mr. David Christy. 



Genus — PHOLIDOPS Hall. 



Pholidops Tkentonensis n. sjp. 



Plate 7, fig. 8. 



Shell small, broadly oval, very depressed-convex. Apex situated 



near the cardinal extremity. Surface marked by strong concentric 



lamellose lines of growth. 



This shell is larger than any other described species, except the 

 P. terminalis from the Oriskany sandstone, at Cuiriberland, Md., 

 and differs from all the others in the regularity of the oval outline, 

 and the proximity of the apex to the cardinal margin. The speci- 

 mens which I have seen do not appear to have the surface so closely 

 marked with squamose lines as most of the other forms. 



Formation and locality. Found on the surfaces of slabs of 

 Trenton limestone, from Middleville, New York, associated with 

 Orthis testudiiiaria. 



Pholidops subtruk-qatus. 



Plate 7, fig. 9. 



Orbicula ? subtruncata : Hall, Palaeontology of New York, Vol. i, p. 290, pi. 79, 



figs. 7«, 7b. 



This species, on examination, proves to be a Pholidops, and dis- 

 tinguished from all the others by its wide and subtruncate posterior 

 border. 



The original is from the shales of the Hudson-river group, at 

 Lorraine, Jefferson county, New York. 



We have therefore two Lower Silurian species of the genus, now 

 known to range from Lower Silurian to Devonian, inclusive. 



Genus — TEEMATIS Sharjje. 

 Trematis millephn-ctata n. sp. 

 Plate 7, figs. 22-25. 

 Shell small, suborbicular, transverse on the ventral side and len- 

 ticular in profile. Yentral valve strongly convex below the middle, 

 more depressed above ; with a narrow deeply depressed pedicle-open- 

 ing, the margins of which are flattened for a space nearly equal to 

 the breadth of the opening. Dorsal valve more elongate, most con- 



