from the Red Crag. 357 



the Pinnigrada ; but a more accurate examination demonstrates 

 its true nature. The crown of the tooth is conical, but not so 

 curved as that of the preceding species, whilst the fang is broad 

 and twisted, an occurrence which is very frequent in the Grampus 

 and larger Dolphins. The enamel is thin, and, in one specimen, 

 has been worn away so as to form a flat surface. This mode of 

 attrition is frequently observable in specimens of Phocana Orca 

 and P. Capensis ; and, indeed, in form and size these teeth agree 

 so well with those of the former species, that I have adopted the 

 specific term orcoides. The base of the fang in the specimen 

 drawn in figs. 14, 15, 16 exhibits a structure to which I am 

 anxious to direct attention, as being characteristic of fossil Ceta- 

 cean teeth. The cement exists in undulating spiral layers sur- 

 rounding the fang, forming slight ridges where the processes of 

 mineralization have removed the more yielding matter. These 

 spirals or circular ridges I have observed on the base of Ceta- 

 cean teeth from Antwerp in the collection of M. Van Beucden ; 

 and a similar structure is to be observed in gigantic dental re- 

 mains from both the Suffolk and Antwerp Crags, which have 

 not yet been assigned to any group of animals. A section of 

 the tooth of the Phoctena orcoides is afibrded by two specimens, 

 and will comi)lctcly confirm the assumption of its Cetacean affi- 

 nities. The lower part of the fang in one tooth is transversely 

 fractured, and shows the osteo-dcntine arranged in concentric 

 layers, and filling up the central cavity, which is thus made 

 solid throughout. The dentine and thickened cement are also 

 seen in section. In another specimen, in which the crown is 

 broken off from the fang, the cavity is still retained, running 

 right into the conical cusp, but is small, and shows signs of 

 thickening in the walls ; the dentine does not occupy much ex- 

 tent, whilst the cement is very largely developed, and is covered 

 by a most delicate layer of enamel. The teeth of the Phocana 

 orcoides are not unlike those of the P. crassidens described by 

 Owen from the fens of Lincolnshire ; but I am not aware of any 

 reasons for supposing that they are specifically identical. I have 

 seen two or three specimens of large petro-tympanic bones from 

 the Crag, evidently belonging to a Grampus about the size of 

 the one which possessed the teeth figured; and I therefore 

 venture to associate them as belonging to the same species. I 

 am not able here to give a figure of this larger cetotolite, but 

 hope hereafter to do so. 



It would be a very desirable thing to identify the tympanic 

 bones described by Prof. Owen as Balana definita &c. with 

 other Cetacean remains ; and I believe that much light will be 

 thrown on this and the nature of the petro-tympanic bones, 

 teeth, and vertebra of the Crag Cetacea generally by mstitutmg 



