792 E. T. NEWTON ON SATTftOCEPBALlTS. 



infer that there were no roots ; but a fracture through the jaw in 

 the region of one of the teeth places this beyond doubt, showing, as 

 it does, that the teeth are hollow, without fangs, and merely ankylosed 

 to the surface of the bone in a manner similar to that which obtains in 

 the fixed teeth of the pike. The points of some of the teeth are seen 

 to be furnished with minute caps of enamelled substance. In Mr. 

 Willett's specimen, figured by Dixon (pi. xxxii*. fig. 10), the bone of 

 the roof of the mouth bears the barbed teeth, and has been regarded 

 as a palatine bone ; but I think there is now evidence of its being 

 the pterygoid, for its anterior part seems to have been attached to 

 another bone ; and furthermore, in a specimen in the Jermyn-Street 

 Museum, there are two bones in this region — an anterior one, which 

 I regard as the palatine, and a posterior one, corresponding with 

 that preserved in Mr. "Willett's specimen, which is probably the 

 pterygoid. Both these bones carry barbed teeth, which are anky- 

 losed in a similar manner to those of the lower jaw. In some of 

 these barbed teeth it may be noticed that the sharp cutting-edge of 

 the front convex border only extends from the apex about halfway 

 down the tooth. 



It is very unlikely that the 8. Leanus of Hays ever possessed pala- 

 tine teeth ; but, however that may be, the mode of implantation of 

 its teeth is totally different from what occurs in the British speci- 

 mens in question ; and the necessity of placing the latter in a separate 

 genus, will, I think, be obvious to all who carefully consider the struc- 

 tural differences which they present. Dr. Leidy had already seen the 

 necessity for this change in 1856, and gave the name of Oimolich- 

 ihys levesiensis to these British specimens. The name of Saurodon 

 Leanus, therefore, must now be erased from our lists of British 



In the year 1845 M. Eeuss (Bohm. Kreide, p. 8) named certain 

 fragmentary barbed teeth Spinax marginatum. These specimens 

 were referred with considerable doubt by M. Hebert (1854, Mem. 

 Soc. Geol. France, ser. 2, vol. v. p. 350), together with others which 

 he describes, to the genus Anenchelum of Blainville (1818, ' Sur 

 les Ichthyolites,' pp. 9, 87), retaining for them the specific 

 name of marginatum. It is probable that these teeth are generically 

 identical with the English ones hitherto referred to the S. Leanus 

 of Hays ; but I do not think we should be at all justified now 

 in placing them in the genus Anenchelum, concerning which so little 

 is known. It may be that Eeuss's specimens will eventually prove 

 to be of the same species as the English ones ; but it seems to me 

 that it would not be right to adopt the name of Cimolichihys mar- 

 ginatum for the English specimens without stronger evidence than 

 is afforded by these isolated teeth. 



Saurocephalus striatus was founded by Agassiz (Poiss. Foss. vol. v. 

 p. 102) upon a fragment of a jaw in Dr. Mantell's collection con- 

 taining three teeth, resembling in form those of the so-called S. lan- 

 ciformis, but much smaller and striated. No mention is made of 

 any series of foramina along the inner aspect of the jaw, which is 



