Mr. A. 8. Woodward on Rhaphiosaurus. 351 
The fossil in question was discovered by Mr. James Carter, 
F.R.C.S., and presented by him to the Woodwardian Museum, 
Cambridge; and, through the kindness of Prof. Hughes, the 
present writer has lately had the privilege of examining and 
comparing the specimen with fossils in the British Museum. 
As a result of the study it may be definitely asserted that 
“Rhaphiosaurus”’ is founded upon the anterior half of the 
dentary bone of a small species of the characteristic Cre- 
taceous fish, Pachyrhizodus, and the resemblance of the den- 
tition to that of the pleurodont lizards is merely a case of 
analogy. 
The jaw exhibits the characteristic fibrous texture of fish- 
bone, and the dentition is such as might from present know- 
ledge be assigned either to fish or reptile; the bone does not 
taper anteriorly, but, when viewed from beneath *, it shows 
the marked inflexion at the symphysis observed in all species 
of the genus just mentioned. The arrangement of the teeth 
agrees precisely with that described by Cope ft and the present 
writer | in Pachyrhizodus; and the dentition is so closely 
paralleled by that of a maxilla in the British Museum asso- 
ciated with scales and detached bones (no. P. 1808), that 
there can be no doubt as to the generic determination. With 
regard to its specific characters, the slenderness and form of 
the dentary bone are sufficient to distinguish it from all 
described species of Pachyrhizodus, and it may therefore retain 
the name of subulidens originally proposed by Owen. The 
British Museum fossil just mentioned is also interesting as 
extending the known range of the form to the Chalk of 
Sussex. 
The intricate history of the acquisition of our knowledge 
of Pachyrhizodus has already been summarized and discussed 
in the ‘Synopsis’ quoted above. Other supposed Saurians 
—NMosasaurus gracilis and Acrodontosaurus Gardneri—have 
likewise been recorded through a misinterpretation of portions 
of jaws of this great predaceous fish ; and it is unfortunate to 
have to add one more of the few Reptilian generic names in 
the list from the European Chalk to the synonymy of the 
same deceptive generic type. 
* Pl. xxxix. fig. 1, in Dixon’s ‘ Geol. Sussex.’ 
{ E. D. Cope, “ Vertebrata of the Cretaceous Formations of the West ” 
(U. 8. Geol. Surv. Territ. 1875), p. 220. 
I Smith Woodward, lve, cit. p. 315. 
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