PHOCENA CRASSIDENS. is iy 
to its length, especially across the mawillary portion: it 
has shorter temporal fossee and more numerous teeth. The 
general resemblance of the fossil to the skulls of the 
Grampus and Round-headed Porpoise is much closer, and 
its distinctive character requires more detailed comparison 
with these for its demonstration. The following are di- 
mensions of the cranium of the fossil and of the closely 
allied recent species :— 
Crassidens. Orca. Melas. 
Th. Ins yin: 
1. Length of the skull from the back part of the condyles 
to the end of the beak . < ° 2 26 36 86.24 
2. Length of the beak from the front end of the malar 
bones . A : ; : 2 12 ele 
3. Breadth of the skull across the post-orbital processes of 
the frontal bones : - : ; 15 21 ~~ L5s 
4. Height of the skull from the lower part of the condyles 
to the top of the occipital crest . : : 95 15 94 
5. Breadth of the beak across its middle part 3 7 10 63 
6. Length of the alveolar series, lower jaw, ‘. 93 15 64 
7. Length of the lower jaw ‘ : : 204 29 19 
These dimensions show the close agreement between 
the fossil and the skull of the Phocena melas in general 
size, but the sixth admeasurement demonstrates an im- 
portant difference in the extent of the dental series: and 
this difference does not depend on a corresponding differ- 
ence in the number of the teeth, which might have been 
merely the effect of age; for the lower jaw of the Ph. 
melas, the subject of comparison, has eleven teeth in the 
alveolar series of each ramus, whilst the fossil jaw has 
only ten. The greater extent of the dental series in this 
jaw depends on the considerably larger size of the teeth 
in the fossil, as the following dimensions show :— 
Crassidens. Orca. Melas. 
In, In. In. 
Circumference of the base of the crown of the largest tooth 2 4 ] 
Length of the crown of do. : : : F 123 = 
