• PALAEONTOLOGY OF NEW-YORK. 



Linjfiila desiderata (n.s.). 



PLATE II. 

 Shell robust, elliptical, convex, the width equal to about four-sevenths 

 of the length, the greatest width being above the middle of the shell. 

 ScRFACE marked by fine and closely arranged concentric striae; the 

 interior of the shell, and the cast, showing strong radiating striae- 

 Length a little less than half an inch. 



The specimen is apparently a dorsal valve, -which is truncate, aud perhaps a 

 little imperfect at the beak. In its general form it resembles L. ligea, but is wider 

 above the centre and more convex, while it is larger than any specimens of that 

 species in the collection. The presence of radiating strja; has not been observed 

 in L. ligea. Other specimens are required for a satisfactory determination of its 

 character. 



Geological formation and locality. In the Corniferous limestone of the Upper 

 Helderberg group, at Lapham's mill, Ontario couuty, N. Y. 



J Liii^la nianni (n.s.). 



PLATE XL 

 Shell somewhat obovate, the cardinal end being narrower and rounded ; 

 gradually expanding in width for more than two-thirds the length, 

 becoming slightly narrower below, with the baso-lateral angles very 

 abruptly rounded : basal margin nearly straight. Surface marked by 

 fine close concentric striae, which are scarcely elevated above the 

 smooth glossy surface. Shell thin : valves nearly flat. 

 One specimen measures three-fourths of an inch in length by half an 

 inch in its greatest width, while the width one-third the length below 

 the posterior end is three-eighths of an inch. 



Two separate valves are all that have been seen of this species, but it differs 

 sufficiently from all the others in these strata to be readily recognized. This and 

 one other are the only species of Linoula, at this time known to me, in the lime- 

 stones of the Upper Heldei'berg group. 



The specimens were received from Dr. R. P. IVIanx, of Milford, Dclawai-e county, 

 Ohio. 



Geological formation and locality. In limestone of the age of the Upper Hel- 

 derberg limestone, in Delaware county, Ohio. 



