474 •'• P- J - Kavn - 



is so great — among other things in the characteristic position of 

 the umbo — that I venture to refer the specimen to A relrotracta. 



Distribution. North-East Greenland: at "4. Samkning" on 

 Store Koldewey Island (1 left valve). 



Russia: in "3. Etage" at Moscow. 



42. Tancredia curtansata PHILLIPS sp. 



(1829) 1835. Corbula curtansata Phillips, Geology of Yorkshire. 1. PI. 3, tig. 27. 

 1854. Tancredia — — ; Morris and Lycett, Mollusca from the 



Great Oolite. III. p. 93: PI. 13, fig. 7. 



The shell rounded, ohliquely triangular. The umbo somewhat 

 behind the middle, little projecting. The anterior part of the shell 

 compressed, pointed; the posterior part moderately arched. The 

 margin in front of the umbo concave; the posterior margin convex, 

 somewhat blunt, the ventral margin evenly curved. The hinge with 

 a cardinal tooth and a long, posterior, lateral tooth in each valve. 

 The surface of the shell with fine and coarse lines of growth. 



A cast of a right shell: height 22 mm, length ca. 33 mm and 

 thickness ca. 5*5 mm. 



Distribution. North-East Greenland: in loose-lying stones 

 at "4. Samkning" on Store Koldewey Island (2 valves). 



England: in Great Oolite and Coralline Oolite. 



•43. Tancredia planata MORRIS A Lycett. 



PI. XXXIII, fig. 10. 



1854. Tancredia planata Morris & Lycett; Mollusca from the Great Oolite. III. 



p. 94; PI. 13, fig. 10. 



Some casts, one of which is almost perfect, seem to agree well 

 with Mourns and Lycktt's above-cited description and figures (espe- 

 cially with fig. 10 b). 



The shell triangular-oval, fairly flat. The umbo small, almost 

 in the middle. The cardinal margin in front of the umbo slightly 

 concave, behind the umbo slightly convex. The anterior margin 

 rounded; the posterior margin likewise rounded, slightly truncate; 

 the ventral margin evenly curved. The hinge not visible for examina- 

 tion. 



The cast of a left valve: height 17 mm, length 25 mm. 



Distribution. North-East Greenland: "Kloft I" on Store 

 Koldewey Island (1 spec). In free-lying stones at "4. Samkning" on 

 the same island (2 spec). 



England: Great Oolite. 



