145 



Not Ttllina oceidenlalii, Morton. —Jour. Ac. Nat. Sc. Phil., 1842, Vol. VIII, 



p. 210, pi. 11, fig. 3, which, according to 

 Owen & Meek, is a Lucina. 



?=Tellm* equilateralis, Meek & Hayden. — 1856. See Meek's Rep. on the Inv. Cret. 



and Tert. Foss. of the U. Miss. Co., p. 196, 

 pi. 39, figs. 5a, b, c. 



Compare also Tellina Roijana, D'Orb. — Pal. Franc, Terr. Cret., Vol. III., p. 422 



pi. 380, figs. 9-11. 



Shell inequilateral, transversely subelliptical, about one-third longer 

 than high, moderately convex, but a little compressed at the sides, test 

 rather thin. Extremities narrowly rounded, the anterior side being the 

 shortest and narrowest of the two ; outline of base forming a broad, 

 semi-elliptical curve. Dorsal margin sloping obliquely and somewhat 

 rapidl}' in front of the beaks, and less so behind them ; beaks small, not 

 prominent or elevated, directed forwards and placed a little in advance 

 of the middle. Postero-dorsal region compressed behind the posterior 

 umboual slopes. 



Surface marked by irregular, concentric striations. Hinge teeth 

 unknown. Pallial sinus elongated, oblique, ascending, with parallel or 

 nearly parallel sides, and narrowly rounded at its inner termination 

 below, but immediately under the beaks. 



Length, fifteen lines and a half; height, ten lines. 



Nanaimo, V. I., Meek (Thracia occidentalis). Lower Shales, Division 

 B, at Gabriola Island (one example with both valves and most of the 

 test preserved) ; also two miles and a half up the Nanaimo Eiver, Y. I., 

 in Division A (four casts with portions of the shell remaining); J. 

 Eichardson, 1872. 



The pallial line and muscular impressions are well defined in most of 

 Mr. Kichardson's specimens, and the shape of the sinus and direction of 

 the beaks both show that the true position of this shell is in one of the 

 subordinate groups into which the Linnisan genus Tellina has been 

 divided, most likely, judging by its external characters only, in Poll's 

 subgenus Peronoea as defined by recent systematists. As far as can be 

 ascertained at present, the line of opening of the valves below is straight, 

 and not cuiwed posteriorly, and this appears to be the only difference 

 between it and Tellina equilateralis of Meek & Hayden, the anal end of 

 which is said to be " slightly flexed to the left." T. occidentalis of Meek, 

 not Morton, is probably only a variety of T. Boy ana, D'Orbigny, in 

 which the beaks are placed a little nearer than usual to the anterior 

 end. 



