CANTIOSCYLLIUM. 195 



2. Scyllium dubium, A. S. Woodward. Plate XLII, figs. 5, 6. 



1889. ScijUinm duhium, A. S. Woodwara, Catal. Foss. Fishes B. M., pt. i, p. 341, pi. xvi, figs. 7, 8. 



Type. — Group of teeth from zone of Tlolaster suhglohosus ; British Museum. 



SjJecific Characters. — Teeth with an extremely slender crown, round in section, 

 gently incurved, not sigraoidally bent, flanked by a single pair of very long and 

 slender, incurved lateral denticles ; outer coronal face smooth, inner face faintly 

 marked with vertical striations in its basal half. 



Description of Specimen. — This species is still known only by the type specimen, 

 which shows clusters of teeth mingled with remains of cartilage. Even in the 

 anterior teeth (PI. XLII, figs. 5, G) the lateral denticles are nearly half as deep as 

 the crown ; all the enamel is smooth and shining, while the striation in the basal 

 half of the inner face is feeble. The root (fig. G) is shaped as in the teeth of S. 

 antiqunm, already described, but the expansions at the ends of the lateral pedicles 

 are so considerable that in the original diagnosis of the species they were mistaken 

 for an additional pair of minute denticles. 



A single vertebral centrum appears to resemble that of )S*. aiitijnnin in not 

 having any calcification outside the primitive double-cone except a single peripheral 

 layer. 



Tlorkon and Localitij. — Zone of Holaster sithglohosns : Dover, Kent. 



Familij Ginglymostomid.e. 

 Genus CANTIOSCYLLIUM, A. S. Woodward. 



Scyllioclus, L. Agassiz, Poiss. Foss., vol. iii, 1843, p. 377 (hi part). 

 Cantioscyllium, A. S. Woodward, Catal. Foss. Fishes B. M., pt. i, 1889, p. 347. 



Generic Characters. — Teeth very small but stout, with a depressed root, which 

 is scarcely bifid. Dental crown produced downwards and forwards over the root 

 mesially, and flanked by one or two pairs of small lateral denticles. Vertebrae 

 large, the centra short and deep in the abdominal region, conspicuously astero- 

 spondylic. 



Tijpe Species. — CantioscyUivm decijrlens, from the English Chalk. 



1. Cantioscyllium decipiens, A. S. Woodward. Plate XLII, figs. 7 — 11. 



1843. Scylliodus aritiquus, L. Agassiz (errore), Poiss. Foss., vol. iii, p. 378, pi. xxxviii, figs. 2, 4. 



1889. Caniioscyllium decipiens, A. S. Woodward, Catal. Foss. Fishes B. M., pt. i, p. 347. 



1894. CantioscijUivm decipiens, A. S. Woodward, Proc. Geol. Assoc, vol. xiii, p. 195, pi. vi, fig. 1. 



1902. Cantioscyllium decipiens, M. Leriche, Ann. Soc. Gcol. Nord, vol. xxxi, p. 104, pi. iii, fig. 4. 



