136 CRETACEOUS LAMELLIBRANCHIA. 



1900. Plicatula Carteeoniana, Wollemann. Die Biv. u. Gastr. d. deiitsch. u. 



hoUiind. Neoc. (Abhandl. d. k. 

 preuss. geol. Land., n. F., pt. 

 31), p. 22. 



Description. — Shell oval, somewhat triangular, oblique; height greater than 

 length. Right valve much inflated, ornamented with usually eight to ten sharp, 

 prominent ribs, which are slightly curved, bear short spiny processes, and are 

 separated by broad furrows ; well-marked growth-lines occur at intervals. Left 

 valve flat or slightly concave ; ribs less prominent, more rounded, and broader 

 than on the right valve, separated by narrow furrows. 



Measurements : 



(1) (2) (3) 



Length .... 17 13 11 mm. 



Height^ .... 21 16 14 „ 



(1 — 3) from Up ware. 



Types. — From the Neocomian of Maisons, near the Ecorces (Doubs). The 

 specimen figured by Keeping is in the Woodwardian Museum. 



Distribution. — Hytlie Beds of Hythe and (Bargate Stone) of St. Catherine's 

 Hill (Guildford). Sandgate Beds of Sevenoaks. Lower G-reensand of Brickhill, 

 Potton, and Upware. 



Plicatula ^equicostata, Keeping, 1883. 



1883. Plicatula ^quicostata, W. Keeping. Foss., etc., Upware aud Brickhill, 



p. Ill, pi. V, fig. 5. 



Description. — Shell small, ovate, oblique, high, very inequivalve, margins 

 rounded. Right valve much inflated, umbonal part prominent, "with a small area 

 for attachment ; ornamented with numerous (about fifty) small, regular, rounded 

 ribs, which curve slightly, are of nearly equal size, and are separated by nariow 

 grooves ; these ribs are crossed by small concentric lamellae, and occasionally by 

 stronger growth-lines. Left valve flat or slightly concave, with similar ornamenta- 

 tion, but the ribs apparently fewer and broader. 



Measurements : 









(1) 



(2) 



Length . 



t 



, 



9 



16 mm. 



Height . 



. 



. 



14 



19-5 „ 



Thickness 



. 



. 



8-5 



11 „ 





(1, 2) from Upware. 



(1) 



the type. 





^ Measured obliquely. 



