On a supposed Tooth 0/ Galeocerdo. 



II. — Note on a supposed Tooth o/" Galeocerdo yrom the 

 English Chalk. By A. Smith WooDWAKD, F.L.S. 



[Plate I. figs. 5-7.] 



Foe some years a small Selachian tooth from the English 

 Chalk has been exhibited in the British Museum among the 

 doubtfully determined series of Notidanus in the anticipation 

 that it might eventually prove to be an abnormal tooth of this 

 genus. Quite lately, however, two more teeth of precisely 

 the same character have come under the writer's notice from 

 the collection of the late Prince of Mantua ; and by the kind- 

 ness of Mr. R. F. Damon, who has purcliased the collection^ 

 these remarkable fossils are now made available for study and 

 description. That the form of tooth in question is normal 

 may thus be assumed with considerable certainty ; and such 

 being the cat^e, it is of extreme interest as exhibiting no 

 superficial features by which it can be distinguished from the 

 genus Galeocerdo, a member of the family Carchariidge. As 

 is well known, all evidence hitherto obtained as to the occur- 

 rence of sharks of this family in Cretaceous formations is very 

 uncertain ; and it is only by examining the inner structure of 

 the detached teeth that they can be distinguished from those of 

 Lamnidai. It is to be hoped, therefore, that an illustrated 

 description of the three new teeth may soon lead to the dis- 

 covery of additional specimens which can be sliced and micro- 

 scopically examined. 



The teeth are shown of tlie natural size in Plate I. 

 figs. 5-7, the first or type specimen being exposed from the 

 inner aspect, the others exhibiting the outer face. The crown 

 is very low and its apex turned sharply backwards ; the 

 anterior coronal margin is gently arched and marked towards 

 the base with a few feeble denticulations ; the apex above the 

 posterior notch is small and narrow; the margin below the 

 posterior notch is much elongated and exhibits from seven to 

 nine conspicuous denticles, decreasing in size backwards. 

 The root is narrow, and the nutritive foramen on the inner 

 side is in a deep vertical groove (fig. 5). 



These Cretaceous teeth are much smaller than those of the 

 typical Galeocerdo of Tertiary and Recent date, and differ 

 from the majority in their remarkably low crown and the 

 relatively small size of the apex of the tooth. They are most 

 nearly paralleled by the teeth named Galeocerdo lutidens from 

 the Eocene of Bracklesham ; but even the latter exhibit a 

 much more prominent apex and relatively smaller posterior 



