277 



ECHINODERMATA. 



Ceinoidea, genus and species uncertain. 

 Portions of small annulated columns. 



BRACHIOPODA. 



Orthis. 



An imperfect ventral valve of a very small, rather coarsely ribbed and 

 probably undescribed species of Orthis, allied to 0. Davidsoni ; and two 

 fragments of a larger and more finely ribbed species. 



Glassia variabilis, Whiteaves. 



Plate 26, figs. 7, 8 and 9. 



Thirteen specimens, which are probably referable to this species. Three 

 of these are figured on Plate 26. See also page 273 ante. 



Rhynchospira Lowi. (N. Sp.) 

 Plate 25, figs. 8 and 9. 



Shell small, somewhat compressed, subcircular and a little wider than 

 long or subovate and longer than wide, but always pointed more or less 

 obtusely behind ; surface of both valves radiately ribbed. 



Ventral valve rather more convex than the dorsal, its umbo rather ob- 

 tuse, or not very prominent or produced, and its beak truncated and per- 

 forate, the perforation being rather large and circular, or nearly circular, 

 in outline. In the median line there is a slightly greater distance between 

 the two ribs that bound it than between any of the others, but there is no 

 distinct mesial sinus in the ventral valve, nor fold upon the dorsal. 



Dorsal valve with an obscure, narrow, longitudinal median depression 

 in the umbonal region, and a small, slightly incurved, and imperforate 

 beak. 



Surface of both valves marked with from about ten to sixteen simple 

 or bifurcating, subangular radiating ribs. 



Characters of the interior of the valves unknown. 



Approximate dimensions of the largest and most perfect specimen 

 known to the writer : length, seven millimetres ; greatest width, eight 

 mm. 



A few specimens, on two small thin and nearly flat pieces of limestone. 



This little shell seems to differ from Rhyncliospira formosa, (the Trema- 

 tospira formosa of Hall,)* from the Lower Helderberg rocks of the State 



* Paleeontology of the State of New York, vol. Ill, pt. 1 (1859) p. 215 ; and pt. 2 

 <1861) pi. 36, figs. 2at; & pi. 95 A, figs. 7-11. 



H 



