l:!2 ("RKTACEOUS LAMELUBILXNCIHA. 



18(55. Cyprina Saussuki, F. J. Pirhl (uid G. Camp'n-he. Foss. Terr. Cri't. Ste. 



Croix (Matter. Pal. 

 Suisse, ser. 4), p. 

 220. 

 — — — 11. t'uqinnid. Moll. Aptifii do I'Espagne, p. 113. 



Tk't>crij)tio)i.'- Shell ii.-^nally <if siniill or moderate size, snb-triangulur, roniHled, 

 often cyreniforni, convex, more or less eonsideniLly inequilateral. T/iinulai- iuai\oin 

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

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

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

 sharjily limited from the long postero-dorsal margin. Umbones pi'diuinent, l)i-(iad. 

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

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

 inconspicuous carina. Hinge not seen. Oi-nanientation consists of grcnvth-lines 

 and numerous minute radial ribs. 



Measurement!:! ; 



All'niUies. — This species is related to C. nuiaild (see ]>. 13 1), but the outline of 

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

 is moi'e convex, the und)ones are broader and not so high, the lunular mai'gin is 

 not so long, and the carina is less distinct. 



ReDuirkfi. — The relative height and length of the shell, and cunse(iuently the 

 outline, vary considerably. 



Much larger and more globose specimens (Plate Xl.X, fig. 1;'>) in which the 

 carina is indistinct, are associated with the normal forms of ('. SuKssiiri, liut are 

 less abundant. At first sight, especially w hen the shell is not (piile ])i'rl'ect, lhe.se 

 appear to be distinct from ('. Saiifisuri, but after compai'ing a number of speci- 

 mens 1 am led to the conclusion that they are only old individuals Avhich have 

 attained a large size. 



Examples of C Sanssnri from Atherfield were idt'utified by I'ictet and 

 C'am|iiche, but, hitherto, no record of the species a[i|>ears to have been made by 

 any English writer. 



Ti/2)e. — From the Aptian of the Perte-du-Rhone. 



Plsfrihiifiint. — Lower (livensand {J'crii(i-])Ci] and Crackei's) of At hertield. 

 Atherlield Beds of llaslemere and lledhill. 



