12 WKALDEN AND rURBECK FOSSTI; FISHES. 



lIorkn)if< and Lonilitics. — Middle Purbeck Beds: Swanage. Wealden : Tilgate 

 Forest. 



3. Hybodus parvidens, sp. nov. PI. IT, figs. 8 — 14. 



1889. Hybodus, sp. inc., A. S. Woodward, Catal. Foss. Fishes, B. M., pt. i, p. 27G, pi. xi, fig. 16. 



Ti/pe. — Tooth ; British Museum. 



Specific CJiaracters. — Teeth small, rarely exceeding a centimetre in longest 

 diameter ; median cone stout and large, elevated and acute in the anterior teeth, 

 low and blunter in the lateral and posterior teeth ; lateral cones two or three on 

 each side, also low and stout ; coronal surface marked bj sparse vertical wrinkles, 

 which extend to the apices of the lateral cones, some usuallj also to the apex of 

 the median cone; occasional small excrescences at the base of the crown. 



Description of Specimen s. —This species is known only by small, isolated teeth, 

 of which the original of PL II, fig. 8, may be regarded as the type specimen. Its 

 median cone is only moderately elevated, flanked with two pairs of very blunt 

 lateral cones, and marked with especially prominent and sparse wrinkles. The 

 original of fig. 9 has a broader and stouter median cone, with three imperfectly 

 separated lateral cones on one side, two on the other, all marked with less sparse 

 Avrinkles. This tooth passes into those shown in figs. 10 and 12, which have a still 

 stouter and less elevated median cone, and doubtless belong to the back of the jaw. 

 They are noteworthy for the slight arching of their base-line, and a larger tooth 

 of nearly the same form (figured in Catal. Foss. Fishes, B. J\I., pt. i, pi. xi, fig. IG) 

 shows some traces of basal excrescences. Fig. 13 represents a larger tooth, with 

 three pairs of lateral denticles, perhaps referable to the middle part of the ramus 

 of the jaw. The originals of figs. 11 and 14, with a more elevated median cone 

 and two pairs of relatively small lateral cones, are evidently anterior teeth, and 

 are remarkable for the small excrescence at the middle of the base of the crown. 



Though much smaller, these teeth closely resemble those of the Upper Jurassic 

 HyhodtiH uhtusns, Ag., in which, the small excrescences at the base of the crown are 

 especially numerous and prominent. 



Horizons and Localities. — Wealden (chiefly Wadhurst Clay) : Hastings. Weald 

 Clay : Berwick, Sussex. 



4. Hybodus striatulus, Agassiz. Plate III, fig. 8. 



1827. " Eesembliug Silurv^," G. A. Mantell, Illustr. Geol. Sussex, p. 58, pi. x, fig. 4. 

 1837. Hybodus striatulus, L. Agassiz, Poiss. Foss., vol. iii, [>. 44, i>l. viiiZ*, fig. 1. 



Type. — Portion of dorsal fin-spine ; British Museum. 



Specific Cliamcters. — Dorsal fin-spines attaining a length of nearly 25 cm., 



