168 CRETACEOUS LAMELLIBRANCHIA. 



A specimen from Lewes, figured by Mantell,' may perhaps be an example of 

 tliis species. 



Bemcirlis. — Only tliree specimens have been seen, all coming from nearly the 

 same horizon. The number of ribs on those from Haling and Gravesend is fewer 

 than on the specimen from Stratford, but in other characters they agree. 



Types.- — In Dr. Blackmore's collection, and in Mr. G. E. Dibley's collection. 



Distribution. — M. cor-anguinum zone of Haling pit, South Croydon, of 

 Gravesend, and of Stratford, near Salisbury. 



Peoten (Chlamys) MiLLERi, Sowerhj, 1836. Plate XXXI, figs. Sa, h, 4, 5, Q,a, h. 



1836. Pecten Milleeii, /. dc C. Sovjcrhy. Trans. Geol. Soc, ser. 2, vol. iv, pp. 



241, 342, pi. xvii, fig. 19. 

 1850. — — A. iVOrhifjny. Prodr. de Pal., vol. ii, p. 169. 



1854. — Milleri, /. Morris. Cat. Brit. Foss., ed. 2, p. 176. 

 1870. — — F. J. Pidet and O. Campiche. Foss. Terr. Cret. Ste. 



Croix (Mater. Pal. Suisse, ser. 6), p. 214. 



Description. — Shell rather small, ovate, nearly equilateral, the dorsal third 

 narrowing rapidly ; height greater than length. Margins well rounded, but the 

 antero-dorsal and postero-dorsal more or less concave, and the former longer than 

 the latter ; inequivalve. Apical angle about 99°. Ears very unequal. 



Right valve slightly convex, flattened, with numerous slightly elevated, rounded 

 radial ribs, which are smooth or slightly scaly, and separated by broader, shallow 

 grooves. Anterior ear long, with a well-marked sinus ; posterior ear much smaller, 

 triangular, with outer angle obtuse. 



Left valve much more convex than the right, especially in the median line 

 towards the umbo ; ornamented with numerous (usually 45 to 54) radial ribs, 

 which are slightly elevated, flattened or rounded, and smooth (except a few of the 

 posterior ribs) ; on the dorsal part the furrows are narrower than the ribs, and 

 pitted, but ventrally they may be broader, and are always shallow. A secondary rib 

 may appear in the furrows towards the ventral border. Anterior ear considerably 

 larger than the posterior, with seven or eight radial ribs and a few growth-lines ; 

 its outer angle almost rectangular. Posterior ear smaller, with obtuse outer angle. 



Measurements : 



(1) 

 Length . 28 . 

 Height . 32 . 



(1 — 6) All from Blackdown. 



' ' Foss. S. Downs ' (1822), p. 203, pi. xxv, fig. 6. 



(2) 



(3) 



(4) 



(5) 



(0) 



26 



. 21 



. 20 , 



. 13 , 



, 12 



29-5 



. 24 , 



. 23 . 



, 15 . 



, 14-, 



