Jrom the Red Crag. 357 
the Pinnigrada ; but a more accurate examination demonstrates 
its true vature. 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 Phocena 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 Beneden ; 
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 Phocena orcoides is afforded by two specimens, 
and will completely confirm the assumption of its Cetacean afli- 
nities. The lower part of the fang in one tooth is transversely 
fractured, and shows the osteo-dentine 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, ranning 
right imto 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 Phocena 
orcoides are not unlike those of the P. crassidens described by 
Owen from the fens of Lincolnshire ; but Iam 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 Balena definita &e. 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 vertebree of the Crag Cetacea generally by instituting 
