322 
SELACHII. 
absent. Shagreen fine, dense; no cephalic spines; large dermal 
hooks upon the claspers of the male. Vertebrae cyclospondylic, 
sometimes feebly asterospondylic. 
Paleeospinax prisons (Agassiz). 
1843. Thyellina prisca, L. Agassiz, Poiss. Foss. vol. iii. p. 378, pi. xxxix. 
figs. 1, 2. 
1872. Pcdceospinax priscus, Sir P. Egerton, Figs. & Descrips. Brit. 
Organic Remains (Mem. Geol. Surv.), dec. xiii. pi. vii. 
1873. Palceospinax priscus , Sir P. Egerton, Quart. Journ. Geol. Soc. 
vol. xxix. p. 420. 
1881. Palceospinax priscus, J. W. Davis, Ann. Mag. Nat. Hist. [5] 
vol. vii. p. 429, pi. xx. 
1883. Palceospinax priscus, 0. Hasse, Neues Jalirb. vol. ii. p. 66. 
1884. Cestracion (Acrodus), C. Hasse, Palaeontogr. vol. xxxi. p. 6, pi. ii. 
figs. 8, 9. 
1888. Palceospinax priscus, A. S. Woodward, Geol. Mag. [3] vol. v. 
p. 499. 
Type. Vertebral column and shagreen. " '^ - 
The type species, of small size. Principal cusp of the anterior 
teeth much attenuated. Shagreen-granules often striated; dermal 
spines of claspers forked. 
Form, Log. Lower Lias: Lyme Regis, Dorsetshire. 
P. 3189. Head and anterior portion of the trunk, described and 
figured by Egerton, Mem. Geol. Surv. dec. xiii, pi. vii. 
figs. 1, 4—6. Ennislcillen Coll. 
P. 3190. Mandible and dentition, described and figured by Egerton, 
loc. cit. pi. vii. figs. 2, 7, 8. The posterior tooth is not so 
smooth as shown in fig. 8, the crown having a more 
beaded appearance, as in Eynechoclus. Ennislcillen Coll . 
P. 3192. Imperfect vertebral column, with shagreen, half of the 
pectoral arch, and the broken second dorsal fin-spine, 
referred to by Egerton, loc. cit. Ennislcillen Coll, 
P. 1297. Crushed and obscure remains of a complete fish, the out¬ 
lines not being recognizable. The specimen is described 
by Egerton in the Quart. Journ. Geol. Soc. vol. xxix. 
p. 420, and shows the relative positions and proportions 
of the two dorsal fin-spines. Both spines (especially the 
first) are considerably worn obliquely at the distal end, 
and Egerton points out that in situation they agree more 
closely with those of Cestracion than with those of Acan- 
