CESTRACIOXTIDiE. 
305 
(b) Cephalic Spines. 
2691. T) T pe specimen of Sphenonchus elongatus, Agassiz, tom. cit. 
p. 202, pi. xxii. a. fig. 18 ; Tilgate Forest. Mantell Coll. 
P. 4919. One small spine, the basal portion of another, and the 
exserted portion of one larger spine : Hastings. 
Dawson Coll. 
VIII. Cretaceous. (a) Dorsal Fin-spines. 
47228. Portion of a small spine, with few widely-spaced sharp ribs ; 
Gault, Folkestone, Gardner Coll. 
30260, 35168, 35352-3, 35461. Nine more or less abraded frag¬ 
ments of spines ; Cambridge Greensand, Cambridge. 
Purchased. 
P. 2173. Two similar fragments ; Cambridge. Egerton Coll. 
P. 4328. Another fragment; Cambridge. Enniskillen Coll. 
P. 2830. Large abraded and crushed spine, described under the 
name of Hybodus complanatus, B. Owen, Geol. Hag. yoI. vi. 
(1869), p. 482 ; Upper Greensand, Maidstone, Kent. 
Enniskillen Coll. 
(b) Cephalic Spine. 
P. 2296. Portion of a spine equalling those of the Liassic Hybo- 
donts in size ; Grey Chalk, Dover, Kent. 
Presented by Mrs. Burton , 1882. 
The following dorsal fin-spines resembling those of Hybodus and 
Acrodus have also been named:— 
Hybodus acanthophorus , T. C. Hinkler, Archiv. Mus. Teyler, vol. v. 
livr. 2 (1880), p. 122, pi. vi. figs. 19-21, pi. iii. figs, 22- 
26.—Keuper ; Hurzburg. 
Hybodus angulatus, G. von Minister, Beitr. Petrefakt. iv, (1841), 
p. 141, pi. xvi. fig. 17.—Trias; S.E. Tyrol. 
Hybodus dewalquei, H. Forir, Ann. Soc. Geol. Belg. vol. xiv. 
(1887), p. 29, pi. ii. fig. 1.—Upper Cretaceous ; Belgium. 
Hybodus eicJiivalcli, Y. Kiprijanoff, Bull. Soc. Imp. Nat. Moscou, 
1853, pt. i. p. 331, pi. vi.; ibid. 1855, pt. i. p. 392, pi. ii./^ 
—Cenomanian ; Government of Kursk, Bussia. 
Hybodus ensatus, L. Agassiz, Poiss. Foss. vol. iii. (1837), p. 51, 
1)1. ix. fig. 12.—Lower Lias; Lyme Begis. fo'/t-sr. 
x 
