302 CRETACEOUS LAMELLIBRANCHIA. 



tuberculate character to the larger concentric ribs. On the posterior part of the 

 shell the concentric ribs bend sharply upwards. 



Remarks. — Only two imperfect specimens of this species have been seen ; it is 

 closely allied to /. lobatus (p. 296), but differs in the presence of radial ribs, the 

 greater development of the larger concentric ribs, and in the greater convexity of 

 the valves. 



Type. — From the Senonian of Quedlinburg. 



Distribution. — Upper Chalk (probably zone of Actinocamax quadratus) near 

 Speeton, and the south of England (probably Kent). 



Inoceeamus tubercdlatus, sp. nov. Plate LIY, fig. 8. Text-fig. 59. 



1882. Inoceramus cakdissoides, H. Schroder. Zeitschr. d. deutscli. geol. 



Gresellsch., vol. xxxiv, p. 271, 

 pi. xvi, fig. 1 (Non Goldfuss). 



Description. — Shell very inequilateral, oblique, much higher than long; dorsal 

 part moderately convex, ventral part only slightly convex. Umbones relatively 

 small, nearly terminal. Antero-dorsal area flattened, nearly smooth. A rounded 

 depression, separated from the posterior wing-like part, passes from the umbo to 

 the postero-ventral extremity. Hinge-line forms less than a right angle with the 

 anterior margin. 



Ornamentation consists of numerous concentric ribs which, at a short distance 

 from the umbo, are crossed by radial furrows, so that the ribs appear then 

 to consist of rows of tubercles ; on the sides of the shell the radial furrows, 

 and consequently also the tubercles, are less distinct than on the middle of 

 the shell. 



Affinities. — This species is allied to I. lobatus and 7. cardissoides, but differs in 

 the greater development of the radial ribs, which give rise to a tuberculate type 

 of ornamentation ; also the stronger concentric ribs which occur in I. cardissoides 

 are small or altogether wanting. The English specimens agree fairly closely with 

 the example figured by Schroder as I. cardissoides. 



Type. — In Dr. Rowe's Collection. 



Distribution. — Upper Chalk (zone of Actinocamax quadratus) of Brighton, and 

 Sewerby (Yorkshire). 



