ELOPID*. 
37 
Genus PACHYRHIZODUS, Dixon. 
[Geol. Sussex, 1850, p. 374 (ex Agassiz MS.).] 
Syn. Megalodon, L. Agassiz (non Sowerby, 1829), Poiss. Foss., Feuill. 
1835, p. 55 (in part). 
Iiypsochn , L. Agassiz, ibid. 1837, p. 104 (in part). 
Raphiosaurus, R. Owen, Trans. Geol. Soc. [2] vol. vi. 1842, 
p. 413. 
Acrodontosaurus, .T. W. Mason, Quart. Journ. Geol. Soc. vol. xxv. 
1869, p. 444. 
An imperfectly-known genus, hitherto represented merely by 
fragments. Parietal bones small and separated by the supra- 
0cci pital ; no deep depression in hinder part of frontal region. 
Teeth robust and conical, fused at their expanded base with the 
supporting bone ; mandible with a single close series nearly regular 
111 size; premaxilla horizontally extended, with a single close 
series of small teeth round the autero-lateral border and two larger 
teeth within ; maxilla robust, with a single series of teeth smaller 
than those of the mandible. Vertebral centra deeper than long, 
slightly constricted, not pitted at the sides. 
Pachyrhizodus basalis, Dixon. 
1850. Pachyrhizodus basalis, F. Dixon, Geol. Sussex, p. 374, pi. xxxiv. 
* figs. 9, 10. 
Type. Premaxilla; British’ Museum. 
The type species, known only by fragments of the upper jaw. 
1 remaxilla narrow, its dentigerous portion about two thirds as 
firoad as long; the small marginal teeth about 9 in number and 
inclined outwards, tho large inner teeth with long and remarkably 
straight crown, which is not hooked. 
Torm. Sj Loc. Turonian : S.E. England. 
49014. Eight premaxilla figured by Dixon, op. cit. pi. xxxiv. fig. 9, 
to be regarded as the type specimen ; probably from the 
Kentish Chalk. The outwardly-inclined bases of four 
marginal teeth are shown, there arc three empty sockets, 
and a fragment of another tooth appears at each end of 
the series. The hinder inner tooth is represented only by 
its socket. Mrs. Smith’s Coll. 
f*- 5655. Portion of premaxilla with similar large inner teeth and 
an abnormal tooth at the base, associated with four 
characteristic vertebral centra and other fragments ; 
Kent. Harford Coll. 
