CATALOGUE OF THE CETACEA. 285 



with the exceistion of those portions of the former which form the deeply -notched lateral walls of 

 the posterior nares, and which are continuous with the very broad lateral expansions of the basi- 

 occipital. The occipital condyles are nearly an inch apart at their closest approximation below; 

 the foramen magnum is large, rounded below, and angular, rather than notched, above. There is 

 a sharp vertical lamina on the inner side of the supra -occipital, extending forward in the median 

 line, nearly an inch from the inner surface of the supra-occipital, and terminating below about 

 half an inch above the foramen in a small triangular tentorium, from which slight laterally 

 extending ridges indicate the boundary of the cerebellar fossa. 



The superior aspect of the cranium presents no very distinctive features. Compared with 

 Clymenia microxjs, Gray, as figured in the Zuvlogy of ihe Erebus and Terror, pi. 25 (also, in Si/}iopsh 

 of Whales and Dolphins, 4to., Gray, 1868, pi. 25), the following differences are noted: The pre- 

 maxillo) are narrower, more elevated above the maxillse, ; the nasal triangle extends half an inch 

 beyond the posterior end of the tooth line instead of falling about as far behind it, and is much 

 more acute in front in D. Bairdii. The posterior angle of the supra - orbital process in D. Bairdii 

 is much less prominent, when viewed from above, than iu microps, and the extension of the max- 

 illaries over the jugals is less elevated, being evenly rounded off at the sides and in front. The 

 supra -occipital is pressed in above the condyles, and the superior portion of it is more roundly 

 convex than in microps. The proportion of the beak to the brain -case is greater than in Cli/iiienia 

 stenorhynchus, Gray, and the beak is wider, both at the notches and anteriorly. The laterally 

 channeled palate would in any case distinguish it from the species of Clyme)na and Sleno, to which 

 it bears a superficial resemblance. In the anterior third of the beak, the premaxillte evenly slope 

 off toward the maxillae in the same plane, and are separated by the mesethmoid cartilage. Behind 

 this, however, the premaxilhe are solidly united, and much more elevated above the maxilhe, 

 forming a ridge with nearly parallel and vertical sides, rounded off above, and attaining a maximum 

 height above the maxillas of 0.43 of an inch. The nasal triangle is evenly excavated, divided by 

 an open suture terminating in a notch above the narial septum. The mesethmoid plate is jjrovided 

 with a submedian ridge, and terminates above in three jioiuts. The nasals are knob -like and 

 rounded transverse, forming the vertex of the skull. 



Cervical VektebEjE. — These are coossified into three groups, as hereafter mentioned; but it is 

 probable that individuals \a,rj in this respect to some extent. The first mass has a total diameter, 

 from point to point of the transverse j^rocesses, of 5.35 inches; and from the middle lower anterior 

 edge of the atlas to the bifurcation of the spinous process of 3.05 inches. The neural arch is 1.10 

 inch high and 1.53 inch wide; the extreme width across the condylar facets is 3.3 inches. The 

 centrum of the third cervical is 1.3 inch wide by 1.0 inch high. The neural arch (incomplete at 

 the top), 0.92 inch high by 1.0 inch wide; the extreme width from jooint to point of the vertebra 

 is 1.65 inch. The fifth cervical has a total width between the points of the lower transverse 

 processes of 1.57 inch. The height of the centrum is 1.1 inch; of the neural arch, 0.8 inch; the 

 width of the centrum is 1.15 inch; of the neural arch, 0.89 inch. The length of that part of the 

 vertebral column comijosed of third, fourth, fifth, sixth, and seventh cervicals is 1.2 inch, and that 

 part composed of the atlas and axis, 1.0 inch more. The neural spine of the seventh cervical is 

 0.8 inch long, and the width from point to point of the transverse processes, 3. 65 inches; of the 

 second thoracic, the spine is 1.6 inch, and the width 3.55 inches. 



The first mass consists of the atlas and axis solidly coossified both by their spines and bodies, 

 so that the only vestige of separation is an ovate and somewhat oblique opening between the 

 pedicels of the arches. The inferior portion of the atlas is much produced forward, giving an 

 oblique appearance to the whole bone, which is of an approximately triangular shape. Its arch is 

 transversely ovate, with a broad triangular space between the condylar facets. The first spinal 

 nerve enters by a shallow groove over the latter. The transverse processes appertaining to the 

 atlas are rather long and obliciuely flattened above and below, with a slight knob, indicating a 

 superior transverse process, just above them. These two processes are separated by a narrow 

 groove from two nodular projections which indicate the corresponding parts in the axis. A slight 

 ridge exists on the inferior surface of the centrum. The neural spine is very broad, stout, and 



