298 A. J. JUKES-BROWNE ON THE RELATIONS OE 



is a Gault form ; but the Cambridge specimens are generally filled 

 with dark phosphate, and appear to be derived*. 



Avicvla grips jsoides, Sow. 



Avicula gryphceoides, Sow. Geol. Trans, iv. pi. ix. f. 3. 



Jnoceramus Coquandianus, D'Orb. Pal. Fr. pi. 403. f. 6-8 ; Pict. 

 & Camp. Ste.-Croix, pi. 160. f. 9, 10. 



This shell, although simulating Inoceramus in form, has a notch 

 below the ear of the left valve and only one cartilage-pit ; it was 

 rightly referred therefore to the genus Avicula, and probably falls 

 under the subgenus Aucella. It is not the Inoceramus gryphceoides 

 of Min. Conch, pi. 584. f. 1, which I agree with D'Orbigny in con- 

 sidering to be only a variety of 1". concentricus, Sow. (see also Pict. 

 & Camp. Ste.-Croix, part iv. p. 119). 



A. gryphceoides ranges from Upper Gault to Chalk-marl ; it occurs 

 in the topmost bed of the Gault, both in Bedfordshire and Folkestone, 

 and is quite as abundant in the Chalk-marl of Cambridge and Beds. 

 "With this range the fossils in the Cambridge Greensand perfectly 

 agree, the delicate shell being often preserved before passing through 

 the mill, and the bare cast being likewise very common. 



At Barton, near the termination of the nodule-bed, this shell is 

 very abundant, being* mostly derived, I believe, from a bed of dark 

 sandy Gault immediately underlying the Chalk-marl at Toddington ; 

 others, however, have certainly lived while the nodules were being 

 drifted into their present position. It appears therefore in both 

 lists. 



Inoceramus sulcatus, Park. 



Inoceramus sulcatus, D'Orb. Pal. Fr. iii. pi. 403. f . 3-5 ; Pict. & Roux, 

 Gres Yerts, pi. 42. f. 1. 



A small fragment, probably belonging to this species, was figured 

 by Mr. Seeley in the Ann. & Mag. Nat. Hist, for 1861, vol. vii. pi. 6. 

 f. 3, under the name of Area sulcata. In a later volume of the 

 same Magazine, however (1866, vol. xvii. p. 178), he himself suggests 

 the possibility of its being really the apex of Inoceramus sulcatus. I 

 entertain little doubt of this being actually the case ; but I am not 

 aware that any other fragments have since been found, except a 

 large specimen in the Museum, the " gisement " of which is some- 

 what doubtful. 



It is certainly remarkable that a shell so characteristic of the 

 lower part of the Upper Gault at Folkestone should be nearly 

 absent in the more northern counties ; but I have never seen a 

 specimen in Bucks, Beds, or Cambridge, except at Ely, where a 

 few specimens have been found. The partial occurrence of this 

 shell is also recorded by M. Renevier ('Faune de Cheville,' p. 101) ; 

 he says, " It is singular that this Inoceramus, so common at the 

 Perte du Rhone, should be so rare at Cheville, and in general 

 among Alpine localities." 



* I much doubt, however, their distinctness from S. gibbosus. The spiny 

 valve closely resembles fig. 3 of MM. Pictet and Campiche j and intermediate 

 forms are found among the Cambridge specimens. 



