Cetacea. 1467 



nal. Sphenoid transverse. Pterygoidal bones arched. Inferior max- 

 illa arched inferiorly, wider at apex than in the middle and much di- 

 lated in the region of the cheeks. Lachrymal bone small ; behind it 

 may be seen a small aperture, which seems to communicate with the 

 cavity of the mouth. Pterygoidal wings large and multisinuate, and 

 palatinal bones small. Inferior maxilla without teeth, but presenting 

 in the middle a small, but deep alveole, which would perhaps have 

 contained at a later period a few small teeth. 



Vertebra;. The vertebral column is formed of 

 7 Cervical vertebrae. 



10 Dorsal. 



11 Lumbar. 

 1 Sacral. 



13 Caudal. 



Total .... 42 vertebrae.* 



Atlas and axis joined together, so as to form in appearance one 

 vertebra with two united spinal processes, and two lateral ones on 

 each side ; above the posterior lateral process, two orifices which com- 

 municate with the spinal cord may be seen, and a notch exists on the 

 anterior side of the upper part of the spinal processes. Third and 

 fourth cervical vertebrae with nearly united spinal processes and very 

 small lateral ones. These are directed forwards in the fourth and 

 backwards in the third. Fifth, with spinal processes nearly united 

 into a V. Sixth, with spinal processes united superiorly. Fifth 

 and sixth, with lateral processes having their apex widened and 

 directed forwards. Several with spinal processes V-shaped, and 

 prolonged in the shape of a beak about 2j in. long ; lateral process 

 rudimentary. All the cervical vertebrae have at the base of their spi- 

 nal processes an angular, lateral projection. First costal vertebra 

 the smallest of the ten, and the narrowest, the tenth the largest and 

 widest; all the costal vertebrae have the summit of their spinal pro- 

 cesses truncate and somewhat rounded at apex. Lateral processes of 

 the base of the spinal ones rugose, and directed obliquely forwards in 

 the seven first, and straight forwards in the three last. The costal 

 vertebrae are notched anteriorly, and posteriorly at the base of the 

 spinal processes. The ribs are more or less depressed and compressed, 



* And not 38, us erroneously indicated by M. Dumortier, Mem. p. 11. 



