212 
DES. A. CAETE AND A. MACALISTEE ON THE 
Each nasal bone was a five-sided mass of light, spongy, osseous tissue, resembling a 
blunt wedge Avith the narroAvest end posteriorly ; its posterior surface was furrowed into 
a number of deep narrow longitudinal sulci for the accommodation of the articular 
lamellae of the frontal bone ; the inferior surface was grooved along its posterior border 
to articulate with the nasal ridge of the frontal, which projected forwards as a shelf to 
support this extremity ; it united externally by a flat surface with the intermaxillary, 
and internally by a similar facet with its felloAv of the opposite side ; the anterior and 
upper surface Avas convex, and Avas broader below than above. 
The inferior maxillary was a curved elongated bone composed of a condyle, coronoid 
process, and ramus. The condyle was divided into two unequal segments by a trans- 
verse sulcus; the upper portion was much the larger, and articulated on a plane ante- 
rior to the occipital condyles Avith the glenoid cavity of the squamous bone, through 
the interposition of a large fibrocartilaginous interarticular cushion ; but, as stated by 
Hunter, no true synovial membrane was found in this articulation, although the 
existence of a double synovial sac has been demonstrated in B. mysticetus by Eschricht 
and Reinhardt. The lower portion formed about one-fourth of the entire condyle, and 
gave insertion to the posterior set of fibres of the depressor muscle of the lower jaw. A 
shallow sigmoid notch, 6 inches wide, separated the condyle from the coronoid process, 
Avhich latter was prominent and directed upAvards and outwards, its posterior margin 
being 2f inches and the anterior 2 inches in height, where it gave insertion to the 
tendon of the temporal muscle. 
The projection of this bony process is one of the distinctive characters of this 
species. 
Below the centre of the sigmoid notch and on the inner surface of the bone the orifice 
of the inferior maxillary canal, for the transmission of the nerves and vessels, AA 7 as situ- 
ated; this canal continued through the ramus, sending off numerous branches which 
opened ultimately by seven oblique foramina in a regular series along the upper border 
of the external surface of the bone. A series of similar but smaller canals, about twenty 
in number, with their orifices directed forwards, perforated the internal surface close to 
its upper edge. The rami were firmly united by a dense fibrocartilage at the symphy- 
sis. The lower jaw projected beyond the intermaxillary bones for about 2 inches, and 
the transverse width between the rami, taken at the point of their greatest convexity, 
which Avas about 1 foot 7 inches from the symphysis, exceeded the transverse width of 
the superior maxillaries, measured from the same place, by about 9 inches ; and each 
ramus towards its anterior extremity exhibited a slight tendency to that torsion Avhich 
is so distinctly marked in the lower jaw of B. mysticetus ; and at the symphysial end 
there was a distinct fissure, the remains of the channel for the distal extremity of the 
Meckelian cartilage. 
The lachrymal bone was in outline a scalene triangle with rounded angles; its external 
border was the thickest and someAvhat concave, its upper margin being raised into a well- 
defined ridge, the other sides being thinned off like a wedge ; the inferior surface Avas 
