CORAX. 



197 



usually notched on the hhider border and with distinct marginal serrations. 

 Vertebral centra strengthened by numerous concentric calcified laminge, as in 

 Selache. 



Type Species. — Gorax pristodontiis, t^'^pically from the Upper Cretaceous 

 (Danian) of Maastricht, Holland. 



B.cmarliS. — This is an essentially Upper Cretaceous 

 genus, though the type species seems to range upwards 

 to the Eocene in Alabama, U.S.A. The teeth are 

 very similar in shape to those of certain Carchariidge, 

 such as Sph-ijriia {Zj/(jxii(i) and CarcJiafias, but are dis- 

 tinguished by the absence of an internal cavity. In 

 microscopic structure (Text-fig. 57) they agree with the 

 teeth of the existing Lamnid'de. It is also noteworthy 

 that with the ordinary teeth are found a few relatively 

 small teeth, which may have occupied a gap near the 

 fi'ont of the series in the upper jaw, as in Lantiia, Ch'i/rJtina, 

 and Odoiitaspis (see Text-fig. 59, p. 199). The vertebral 

 centra occur in association with teeth and pieces of carti- 

 lage in two specimens from the Niobrara Chalk of 

 Kansas (B. M. nos. P. 9199, P. 10310). They are very 

 short in proportion to their diameter, and are all nnich 

 distorted by crushing in the fossils. As seen in cross- 

 section, the secondary calcifications round the piimitive 

 double-cone are chiefly delicate concentric lamellas, and 

 there are deep wedge-shaped cavities which were origin- 

 ally filled by the uncalcified cartilage at the bases of the 

 appended arches. 



Fui. 57. Gorax ; vertical trans- 

 verse section of tooth, highly 

 magnified, showing the super- 

 ficial gano-dentine and the 

 vaso-dentine, without an in- 

 ternal cavity. After Agassiz. 



1. Corax pristodontus, Agassiz. Plate XLII, figs. 12 — 15; Text-figure 58. 



1843. Corax pristiidoiitns, L. Agassiz, Poiss. Foss., vol. iii, p. 22 i, pi. xxvi, figs. 9 — 13. 



1889. Curax pristodontus, A. S. Woodward, Catal. Foss. Fishes B. M., pt. i, p. 423. 



1891. Corax pristodontus, A. S. Woodward, Geol. Mag. [3J, vol. viii, p. 112, pi. iii, figs. lU— 16. 



1894. Corax ^pristodontus, A. S. Woodward, Proc. Greol. Assoc, vol. xiii, p. 198, pi. vi, figs. 16 — 18. 



Ti/pe. — Detached teeth from the Danian of Maastricht, Holland. 



Specific Characters. — The type and largest known species, the teeth sometimes 

 measuring 3 cm. in diameter. Teeth low and broad with a very large root ; 

 anterior border gibbously arched ; posterior border often not notched, only slightly 

 concave ; serrations always distinct. Root of teeth without any median cleft for 

 a nutritive foramen on its inner face. 



Description of Specimens. — An associated set of teeth discovered by M. Houzeau 



