LIMA. 29 



1895. LIMA COTTALDINA, G. Maas. Zeitschr. der deutsch. geol. G-esellsch., vo . 



xlvii, p. 267. 



(RADULA) COTTALDINA, F. Vogel. Hollandisch. Kreide., p. 56. 

 1900. COTTALDINA, A. Wollemann. Die Biv. u. Gastrop. d. deutscli. u. 



Holland. Neocoms (Abliandl. d. k. 

 preussisch. geol. Land., N. F., pt. 

 31), p. 35, pi. ii, figs. 2, 3. 



Non 1847. PABALLELA, d'Orbigny. (See p. 31). 



Description. Shell moderately convex, oblique, oval or rounded-oblong, higher 

 than long. Antero-dorsal margin long, nearly straight, more or less parallel with the 

 postero-ventral margin ; postero-dorsal margin short, more or less nearly straight. 

 Anterior margin regularly rounded. Umbones sharp, only slightly curved ; apical 

 angle about 90. Ears of moderate size. Anterior area rather large, slightly 

 convex ventrally, depressed near the umbo, usually smooth except for growth- 

 lines. 



Ornamentation consists of 18 to 20 principal ribs, and sometimes of a few 

 smaller ribs near the posterior margin. The principal ribs are roof-like with sharp 

 summits ; they are strongest on the antero-dorsal part of the valve and become 

 less elevated and rather more widely separated in passing posteriorly ; the two or 

 three anterior ribs (near the anterior area) are rather smaller and closer together. 

 A small rib occurs at the bottom of the furrows between the main ribs ; smaller 

 linear ribs may occur on the sides of the principal ribs, especially on the posterior 

 part of the shell. Fine concentric growth-lines are seen on the ribs and furrows. 



Measurements : 



(1) (2) (3) (4) (5) (6) (7) (8) 



Length . 26 26 25 23 23 22 19 14mm. 

 Height . 21 22 20 19 18 17 16 11 

 (1, 4) Perwa-bed, Atherfield. 

 (2, 5) Hythe Beds, Lympne. 



(3) Lower Greensand, Upware. 

 (6, 7) Hythe Beds, Hythe. 



(8) Ferruginous Sands, Shanklin. 



Affinities. This species is closely allied to L. Royeriana, d'Orbigny, 1 but in 

 the latter the ribs do not decrease in size nor become more widely separated on 

 the posterior part of the shell, and the small rib in the furrows is absent or 

 indistinct. 



L. parallela is distinguished from L. gaultina (p. 31) by being relatively 

 shorter and less compressed, by the ribs on the posterior part of the shell being 



1 'Pal. Fran?. Terr. Cret.,' vol. iii (1847), p. 527, pi. ccccxiv, figs. 5 8; Pictet and Campiche, 

 ' Terr. Cret. Ste. Croix ' (1869), p. 142, pi. clxiv, figs. 4, 5. 



