132 CRETACEOUS LAMELLIBRANCHIA. 



1865. Cyprina Saussuki, F. J. Pictet and G. Campiche. Toss. Terr. Cret. Ste. 



Croix (Mater. Pal. 

 Suisse, ser. 4), p. 

 220. 

 H. Coquand. Mon. Aptien de l'Espagne, p. 113. 



Description. — Shell usually of small or moderate .size, sub-triangular, rounded, 

 often cyreniform, convex, more or less considerably inequilateral. Lunular margin 

 of moderate length, concave. Anterior margin regularly rounded, passing gradu- 

 ally into the convex ventral margin. Posterior margin short, often more or less 

 rounded, sometimes truncate, forming an angle with the ventral margin, and not 

 sharply limited from the long postero-dorsal margin. Umbones prominent, broad. 

 Carina rounded, sometimes rather indistinct. Postero-dorsal area narrow. 

 Lunular region deep, indistinctly limited. Escutcheon elongate, bounded by an 

 inconspicuous carina. Hinge not seen. Ornamentation consists of growth-lines 

 and numerous minute radial ribs. 



Measurements .• 



(i) 



(2) (3) (4.) (5) (6) (7) 



(8) 



(9) 



Length 



52 



49 40 38-5 38 33 2(3 



25-5 



24 mm. 



Height . 



40 



40 31 33 31 27 21 



21-5 



L9 „ 



Thickness 



34 



31 27 2G 20 16 

 (1,2) Pema-heA, Atherfield. 

 (3-9) Crackers, Atherfield. 





14- „ 



Affinities. — This species is related to G. cuneata (see p. 134), but the outline of 

 the shell is less distinctly triangular, the sides are less flattened, the ventral margin 

 is more convex, the umbones are broader and not so high, the lunular margin is 

 not so long, and the carina is less distinct. 



Remarks. — The relative height and length of the shell, and consequently the 

 outline, vary considerably. 



Much larger and more globose specimens (Plate XIX, fig. 13) in which the 

 carina is indistinct, are associated with the normal forms of C. Saussuri, but are 

 less abundant. At first sight, especially when the shell is not quite perfect, these 

 appear to be distinct from G. Saussuri, but after comparing a, number of speci- 

 mens I am led to the conclusion that they are only old individuals which have 

 attained a large size. 



Examples of G. Saussuri from Atherfield were identified by Pictet and 

 (ampiche, but, hitherto, no record of the species appears to have been made by 

 any English writer. 



Type. — From the Aptian of the Perte-du-Rh6ne. 



Distribution. — Lower Greensand (Perna-loed and Crackers) of Atherfield. 

 Atherfield Beds of ETaslemere and Redhill. 



