334 
SELACHII. 
25858. Type specimens, figured, of the natural size, in PI. XIII. 
figs. 11, 12; Upper Greensand, Maidstone. Dixon Coll. 
39217. Two teeth, one relatively narrow and tapering at each extre¬ 
mity ; Maidstone. DowerbanJc Coll. 
P. 2125. Two teeth named “ Strophodus sulcatus ,” in Agassiz’s hand- 
Maidstone. Egerton Coll. 
writing; 
/ P. 2664. Imperfect abraded tooth; Maidstone. Ennislcillen Coll. 
Cestracion canaliculatus, Egerton. 
1850. Cestracion canaliculatus, Sir P. Egerton, in Dixon’s Foss. Suss, 
p. 365, pi. xxxii.* fig. 8. 
1850. Acrodus cretaceus, F. Dixon, op. cit. p. 364, pi. xxx. fig. 13. 
1853. Cestracion canaliculatus, Sir P. Egerton, Quart. JournrGeol. Soc. 
vol. ix. p. 281. 
1872. Di'epanephorus canaliculatus, Sir P. Egerton, Figs. & Descrips. 
Brit. Organic Remains (Mem. Geol. Surv.), dec. xiii. pi. ix. 
1883. Cestracion canaliculatus, C. Hasse, Neues Jahrb. vol. ii. p. 66. 
1887. Drepanephorus canaliculatus, A. S. Woodward, Geol. Mag. [3] 
vol. iv. p. 105. 
1888. Drepanephorus canaliculatus, A. S. Woodward, Proc. Geol. Assoc, 
vol. x. p. 290. 
Type. Associated teeth. 
Anterior dorsal fin-spine placed approximately over the twenty- 
fifth vertebra. Extremities of the principal lateral teeth rounded, 
and the longitudinal coronal keel in these raised mesially into a low 
rounded eminence; root pierced by a. large oblique perforation. 
Form. Sf Log. Senonian: S.E. England. 
^ 49735. The right pterygo-quadrate and mandibular cartilages, with 
the anterior extremity of the left mandibular, preserved in 
the two halves of a small block of chalk; Upper Chalk, 
Guildford, Surrey. Though much crushed and broken, 
the pterygo-quadrate has the appearance of being notably 
longer than the mandibular. A few of the anterior teeth 
are displayed, and two are shown, of three times the 
natural size, from the posterior and anterior aspect respec¬ 
tively, in PI. XI. figs. 24, 25; each has one pair of broad 
lateral denticles. Some of the principal lateral teeth of 
the upper jaw also occur in position. Those of the largest 
series (PI. XI. fig. 26) measure 0-007 in length, and those 
of the series immediately behind (PI. XI. fig. 26) 0-005 ; 
