312 
SELACHII. 
Yar. fiettonensis. Tubercles upon tbe dorsal fin-spines com¬ 
paratively small, fused into ridges distally. Teeth of series iv. 
narrow ; coronal prominence in most teeth well marked. 
39475. Fragment of spine ; Upper Oxford Clay, Chippenham. 
Purchased, 1865. 
P. 5881. Plaster cast of cephalic spine, described and figured by the 
present writer, Joe. cit. p. 340, pi. xii. figs. 7,8 ; Oxford 
Clay, Fletton, near Peterborough. 
Made in the Museum, 1888. 
47440. Forty-four associated teeth ; Fletton. Two of series iv. are 
shown, of the natural size, in Plate XY. fig. 14. 
Sharp Coll. 
I. Species founded upon detached dorsal fin-spines with which the 
teeth have not yet been found associated. 
Asteracanthus semisulcatus, Agassiz. 
1837. Asteracanthus semisulcatus, L. Agassiz, Poiss. Foss. vol. iii. 
p. 34, pi. viii. a. figs. 7, 9, 10 (P fig. 8). 
1871. Asteracanthus tenuistriatus, J. Phillips, Geol. Oxford, p. 178, 
diagr. xxxviii. fig. 7. 
Type. Imperfect dorsal fin-spine ; British Museum. 
Dorsal fin-spine about equal in size to that of A. acutus , but less 
laterally compressed and more robust; anterior face rounded, but 
keeled; posterior face slightly convex, with large denticles. Orna¬ 
mental tubercles relatively large, elongated, arranged in close series, 
often fused in part into short ribs. 
The teeth of this species are probably described under the name 
of Strophodus magnus, Agassiz. 
Form. 6f Loc. Great Oolite : Oxfordshire. 
P. 2855. Type specimen described and figured by Agassiz, loc. cit. 
fig. 7t, Stonesfield Slate, Stonesfield. Enniskillen Coll. 
P. 463. A smaller imperfect spine^gssociated with this species by 
Agassiz (loc. cit. fig. 8),^but exhibiting striking resem¬ 
blances to A. acutus ; Stonesfield. Egerton Coll. 
P. 2856-7. Two abraded fragments of spines equal in size to the 
type, and one imperfect larger specimen; Stonesfield. 
Enniskillen Coll . 
