502 A. J. JUKES-BROWNE'S SUPPLEMENTARY 



specimen in the Woodwardian Museum presents the characters 

 above mentioned. The ribs are strongly marked on the casts ; the 

 shell varies in length from 13 to 17 lines. D'Orbigny gives it as a 

 Turonian form ; but it appears also to occur in the Gault Superieur 

 of Cheville (' Renevier,' p. 163). 



Lima Rauliniana, D'Orb. 



Lima Rauliniana, D'Orb. Pal. Fr. iii. pi. ccccxvii. figs. 5-8. 



This species bears a considerable resemblance to Lima aspera, 

 Mant. : and the Cambridge specimens have hitherto been confounded 

 with that form. 



Great differences, however, are discovered on a close examination. 

 L. aspera has wide, flattened ribs, separated by very narrow inter- 

 spaces, mere grooved lines, in fact, which are pitted at intervals. 



L. Rauliniana has low rounded ribs with peculiar imbrications, 

 and the interspaces are nearly as wide as the ribs. M. d'Orbigny's 

 description is correct so far as it goes ; and fig. 7 shows the peculiar 

 ribs " sur lesquelles sont comme des tuiles obliques en dehors, 

 espacees ot alternes ;" he does not, however, mention the ornamen- 

 tation of the interspaces ; these are not pitted, but crossed with 

 irregular transverse grooves or striations, very minute and closely 

 set. 



The main characters of the shell may be thus described : — valves 

 nearly equal and equiconvex, each bearing between 40 and 50 low 

 rounded ribs, interrupted occasionally by the lines of growth ; the 

 ribs are ornamented with elongate imbrications, projecting slightly 

 over their inner side, viz. over the left side of one half of the ribs, 

 and over the right side of the other half, on each side of a median 

 line, where the ribs divaricate ; when worn, the ribs appear to be 

 simply notched ; the interspaces are grooved in the way above 

 mentioned. 



The specimens are generally preserved in the lighter-coloured 

 phosphate, which at one time I thought had been formed in situ : 

 I have since, however, been led to think that these phosphates have 

 also been derived, but probably from rather higher beds of the 

 Gault than those from which most of the black nodules came. 



Lima Rauliniana is found in the Gaize or Gault Superieur of the 

 Paris basin ; and casts of similar shape are quoted from Cheville by 

 Prof. Renevier (Taune de Cheville,' p. 163) ; but I am not aware 

 that it has been previously discovered in England. 



Lima interlineata, new sp. PI. XXI. fig. 10. 



Shell transversely oval, or obliquely quadrate : valves equiconvex, 

 and each ornamented with 10 or 11 strong rounded ribs radiating 

 from the umbo ; interspaces wide and flat, marked with a few 

 distinct longitudinal lines, which vary in number from 1 to 5, but 

 are most numerous on the more central interspaces. There appear 

 to have been several stronger striae or small ribs on the anterior 

 side or buccal region ; but the shell is here worn off. 



