STROPHODUS RIGAUXI. 31 



those of series 1 strongly arched, the apex of the crown being a blunt point, 

 and the longitudinal keel prominent. 



Distribution. — There are six convex teeth from Peterborough district from 

 the Enniskillen collection in the British Museum, and a large specimen from 

 Botolph's Bridge in the Sharp collection, with five others from the same collection 

 in the Sedgwick Museum. Partly on account of its corresponding size, 8. tenuis 

 is supposed to represent the teeth of the same animal as that to which Astera- 

 canthus acutus belongs. 



Strophodus rigauxi, Sauvage. Plate I, fig. 8 <t, h. 



1867. Curtodus rigauxi, Sauvage, Cat. Poiss. Second Boulonnais, p. 53, pi. iii, fig. 7. 

 1887. Strophodus rigauxi, Platnauer, Yorks. Phil. Soc. Rep., 1886, p. 36, figs. 1, 2. 



Slciatype. — The single tooth which served as type is described as oval and 

 raised in the centre, the reticulations radiating from the highest point, arranged 

 like a lozenge on the higher parts, but becoming more elongated on the sides. 

 From the Bathonian of Marquise. At the time of this description the Cornbrash 

 was included locally with the Bathonian. 



Description. — The tooth described by Platnauer comes from the Cornbrash on 

 the north side of Scarborough Castle. It is of small size and has a coarsely 

 reticulated, not much raised, crown, though it differs from the type in shape. It 

 is, no doubt, one of the posterior series and may be a distinct type. It is referred 

 by A. S. Woodward to 8. magnus, but though the posterior teeth of that species have 

 coarser reticulations than the more anterior, yet they do not approach the coarse- 

 ness of 8. rigauxi, and this coarseness appears to be of more significance than the 

 shape. It is to these higher beds that we have to go to seek an analogy, as in 

 8. reticuiatus. It also resembles very closely the posterior tooth figured by 

 A. S. Woodward in 'Ann. & Mag. Nat. Hist.,' ser. 6, vol. ii, pi. xii, fig. 4, as 

 belonging to A. ornatissimus, var. fiettonensis, from the Oxford Clay of Peter- 

 borough. In any case it is desirable that it should be recognised as the only 

 tooth of StropJiodus occurring in Yorkshire. 



