35 



other about one line at the margin ; the intervening spaces, concave or 

 nearly flat. 



This species closely resembles 0. pectinella, Conrad, of the Trenton 

 limestone, and seems to belong to a group not common in the Devonian. 

 Locality and Formation. — Indian Cove,Gasp^ ; Gasp^ limestone, No. 8. 

 Collector. — R. Bell. 



Orthis Lucia. (N. sp.) 



Plate 3, fig. 4, 4a. 



Description. — Shell sub-circular ; outline concave on each side of the 

 beak ; cardinal angles broadly rounded ; sides gently convex ; front either 

 broadly rounded or with sometimes a portion in the middle slightly project- 

 ing. Ventral valve moderately convex, most prominent about the middle or 

 a little above ; cardinal margin and sides slightly compressed ; umbo well 

 developed, carinating the valve in the upper half ; beak minute, incurved 

 at a right angle over that of the dorsal valve, and apparently in contact 

 with the same ; area very small, scarcely visible. Dorsal valve very 

 slightly convex ; a barely perceptible mesial depression originating in 

 a point at the beak and gradually widening to the front, where it flattens 

 about one half the whole width of the valve. Beak minute, but distinctly 

 visible when that of the opposite valve is removed; cardinal edge slightly 

 sloping on each side of the beak ; area not visible. 



Surface with fine sub-angular striae which bifurcate several times ; 

 those at the cardinal angles, and for some distance below, curving 

 upwards as they approach the margin ; four or five striae in the width of 

 one line. 



Width of the largest specimen seen, eleven lines ; length, about nine lines. 

 Closely allied to 0. planoconvexa, Hall, Pal. N.Y., vol. 8, pi. 12, but 

 differs in having no area as that species has. 



Locality and Formation — Indian Cove, Gasp^, in limestone ISTo. 8. 

 Collector.— T. C. Weston. 



Genus Rhynchonella. (Fischer, 1809.) 



In the 4th vol. Pal. N.Y., Prof. Hall has pointed out, that in many of 

 the fossil species that are usually referred to this genus, there is, in the 

 dorsal valve, a mesial septum, that divides the cavity of the umbo into 

 two compartments, and often supports a small sub -triangular chamber 

 beneath the beak. In a number of empty shells of a species, from the 

 Black River limestone, in our collection,this structure is well exhibited. In 

 the recent species, B. j.sittacea, with which I have compared our fossil 

 specimens, this septum does not exist. There is only a faintly elevated line 



