CHIROCESTTBIDJE. 
95 
Portheus mantelli, Newton. 
1822. “Unknown fish,” G. A. Mantell, Foss. South Downs, p. 241, 
pi. xlii. tigs. 1, 3, 4. 
1835. Megalodon sawoides, L. Agassiz, l’oiss. Foss., Feuill. p. 55 
(name only). 
1836. Meyalodon? leicesiensi.i, G. A. Mantel], Descript, Catal. Geol. 
&c. Mus. Sussex Sci. Lit. Inst. ed. 5, p. 30. 
1837-44. Iltjpsodon leiocsiensis, I,. Agassiz, Poiss. Foss. vol. v. pt. i. 
p. 100 (in part), pi. xxv b. figs. 1, 2. 
1877. Portheus mantelli, E. T. Newton, Quart. Journ. Geol. Soc. 
vol. xxxiii. p. 510. 
Type. Imperfect left maxilla and premaxilla ; British Museum. 
A species of moderate size, the upper jaw attaining a length of 
about O' 18. Premaxilla with five teeth of unequal size. Maxilla 
about four times as long as the premaxilla, and its oral border in 
the form of a slightly concave arch. Teeth smooth, not facetted. 
Form. Loc. Turonian : Sussex. 
4066-67. Type specimen, the promaxilla being in counterpart ; 
Chalk, Lewes. Mantell Coll. 
Portheus daviesi, Newton. 
1877. Portheus damesii, E. T. Newton, Quart. Journ. Geol. Soc. 
vol. xxxiii. p. 511, pi. xxii. fig. 13. 
Type. Right maxilla ; British Museum. 
A species of moderate size, known only by the maxilla, which is 
unusually robust and exhibits a slightly convex oral border. The 
teeth are smooth and not facetted, largest in the middle of the bone 
at the summit of the convexity. 
Form. Loc. Turouian : Kent. 
28388. Type specimen, the right maxilla associated with a ver- 
tebral centrum and an imperfect undetermined bone ; 
Lower Chalk, near Maidstone. Mantell Coll. 
Portheus gaultinus, Newton. 
[Text-figure 5.] 
1877. Portheus gaultinus, E. T. Newton, Quart. Journ. Geol. Soc. 
vol. xxxiii. p. 512, pi. xxii. figs. 1-12, and woodcut. 
Type. Imperfect head and associated vertebra) ; Museum of 
Practical Geology, London. 
A species of moderate size, the cranium attaining a length of 
about 0-2. Premaxilla with five teeth, the second and third much 
larger than the others. Maxilla four times as long as the pre- 
