292 
SELACHII. 
slightly divided into two unsymmetrical eminences, one 
smaller than the other, with traces of lateral denticles. 
Eger ton Coll. 
P. 2734. Eight pterygo-quadrate and mandibular cartilages, with 
about twenty teeth, much displaced. Enniskillen Coll. 
39925. Plaster cast of the dentition probably of the lower jaw, 
described and figured by E. C. H. Pay, loc. cit., and shown 
in the accompanying woodcut (fig. 10); original in the 
collection of S. H. Beckles, Esq., of St. Leonards. 
Purchased , 1866. 
P. 2732. Portions of the dental series n. to vi. of one half of a 
similar, but larger jaw, shown of the natural size in 
PI. XIY. fig. 4. The length of the teeth of the successive 
series is as follows :—n. 0*019, hi. 0*024, iv. 0*028, 
v. 0*024, vi. 0*016. Slight indications of lateral pro¬ 
minences are observed in nearly all the teeth, and the 
coronal contour is much raised in series ii. to iv. In 
series v. the teeth are very obtuse in front, but gradually 
taper behind: and those of no. vi. are comparatively 
narrow, tapering at each extremity. Enniskillen Coll . 
32751. A group of teeth, also probably of the lower jaw, having 
less elevated crowns than in the last specimen. 
Purchased , 1857. 
P. 2137-8. Three small groups of typical teeth. Egerton Coll. 
32752. Eive detached teeth, the crown of one divided into two well- 
marked eminences, and three of the others approaching a 
similar form. Purchased , 185/. 
P. 2139. A posterior series of four small teeth, and nine detached 
teeth. Egerton Coll. 
P. 2745. Elongated principal tooth, the crown marked by two 
faint transverse constrictions. Enniskillen Coll. 
As already remarked (p. 267) the dorsal fin-spines of Acrodus 
anningice can scarcely be distinguished from those of Hyboclus 
reticulatus. They were first described by E. C. H. Day (loc. cit.), 
who pointed out that the second dorsal formed the type of Agassiz s 
Hybodus curtus. The first dorsal is long and slender, and seems to 
differ from that of PL. reticulatus in the more rounded character of 
the ribs and the relatively wider spaces between those placed 
anteriorly. The posterior face bearing the denticles is not much 
