432 CRETACEOUS LAMELLIBRANCHIA. 



Affinities. — Only two right valves of this species have been seen. They 

 resemble closely Gapsa elegans, d'Orbigny, 1 but the ribs on the posterior part of the 

 shell are more numerous and less coarse. 



Distribution. — Upper Greensand (zone of Schloenbachia rostrata) of Blackdown 

 and Hal don. 



Leptosolen ? KECTANGULARis (Woods), 1897. Plate LXIT, figs. 15 — 17. 



[Omitted from Vol. II, p. 221.] 



1897. Trapezium rectangulare, H. Woods. Quart. Journ. Geol. Soc, vol. liii, 



p. 392, pi. xxviii, figs. 11, 12. 



Description. — Shell more or less oblong, very inequilateral, moderately convex, 

 with flattened or slightly concave sides. Anterior part not so high as the posterior 

 part. Postero-dorsal margin nearly straight and nearly parallel to the ventral 

 margin ; anterior margin rounded ; posterior margin truncated, slightly convex or 

 nearly straight, and almost at right angles to the postero-dorsal margin. Umbones 

 inconspicuous, with a carina extending in a curve to the postero-ventral angle, and 

 limiting a triangular postero-dorsal area. A strong internal ridge extends from 

 the umbo towards the opposite ventral margin. Length 19 mm., height 11 mm. 



Affinities. — A similar species has been referred doubtfully by Weller 2 to 

 Leptosolen. Modiola tetragona, Reuss, 3 also shows some resemblance to the English 

 species. The hinge is not shown in any of the specimens, and the generic position 

 must be regarded as uncertain. 



Type. — In the Sedgwick Museum, Cambridge. 



Distribution. — Chalk Rock of Cuckhamsley, Berkshire. 



Vol. II, page 230, line 5 from the bottom, for " varians " read " rostrata." 

 Theacia? gracilis (Sowerby), 183G. Plate LXII, figs. 18, 19. 



[Omitted from Vol. II, p. 244.] 



1836. Psammobia? gracilis, J. de C. Sowerby. Trans. Geol. Soc, ser. 2, vol. iv, 



pp. 242, 341, pi. xvi, fig. 12. 

 1850. Tellina gracilis, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 159. 

 1854. Psammobia gracilis, J. Morris. Cat. Brit. Foss., ed. 2, p. 222. 



1 ' Pal. Fran?. Terr. Cret.,' vol. iii (1845), p. 423, pi. ccclxxxi, figs. 1, 2. 



2 ' Cret. Palseont. New Jersey ' (1907), p. 626, pi. lxx, fig. 29. 



3 'Die Verstein. der bohm. Kreideformat.,' pt. 2 (1846), p. 15, pi. xxxiii, fig. 6. 



