292 APPENDIX. 
inch above the foramen magnum, the broad arch of the tentorium, as long in its axial diameter as 
the septum, extends on each side a little farther than the upper exterior angles of the condyles, 
thence giving out a triangular wing on each side, which, attenuating as it descends, reaches the 
floor of the brain cavity in advance of the opening between the alisphenoid and ex -occipital, and 
is ankylosed with the former. The cerebellar fossa is thus almost cornrdetely inclosed, communi- 
cating with the cerebral fossa only by an opening in the front of the arch but little larger than 
the foramen magnum, and by the narrow openings between the outer edges of the wings of the 
tentorium, bounded below by the alisphenoid, and laterally by the ex -occipital wall. The septum 
ceases abruptly in front, below the frontal and supra -occipital suture. A ridge from the front of 
the tentoxial wings is coossified with the orbito- sphenoid, above the sphenoidal fissure; the latter 
in this species being posterior to and distinct from the foramen rotundum, which opens into the 
cerebral cavity. 
In No. 2, the dimensions were constantly smaller, the skull belonging to a younger, though 
fully adult individual. The teeth were |g 7 , the tip of the lower jaws being mutilated. The ten- 
torium presented the same features as in No. 1, and the skull offered no special peculiarities not 
common to the other. 
The scapula and cervical vertebra of a third specimen, of which the entire skeleton was 
preserved, offered the following peculiarities : The external face of the scapula is flattened, slightly 
excavated in the middle, and with a slight ridge behind. The prescapular fossa is inconspicuous, 
but has a width of three - quarters of an inch on the outer face of the scapula, above the acromion. 
The latter is t/i shaped, notched above behind, with a projecting process below in front. The 
upper anterior corner is connected with the anterior angle of the prescapular fossa by a strong 
ligament ; the anterior termination of the acromion is incurved, and externally convex. The cora- 
coid is triangular, with the distal edge thickened, anteriorly excavated, and knobbed at the corners. 
The external surface is concave. The glenoid cavity is sub-rotundate ; the post - scajmlar edge is 
evenly rounded in a sigmoid curve. Beyond the upper posterior corner a triangular mass of 
cartilage extends beyond the bone, an inch in its greatest width. The inner face of the scapula 
is flattened, with three or four narrow low ridges radiating from the glenoid border. The inner 
surface of the coracoid is convex, and of the acromion concave. The measurements are as follow, 
in inches and decimals : 
Greatest length of scapula 9 .50 
Greatest length of acromion 3 .00 
Greatest length of coracoid 2 .25 
Greatest diameter of glenoid cavity 1 .30 
Glenoid cavity to anterior angle 6 .25 
Glenoid cavity to superior border 6 .00 
Glenoid cavity to posterior angle 6 .00 
Glenoid cavity to anterior angle of acromion 4 .50 
Glenoid cavity to anterior angle of coracoid 3 .00 
Glenoid cavity to posterior angle of coracoid 2 .00 
The cervical vertebrte offer some differences from those of Delphinus Bairdii. The atlas and 
axis are solidly coossified by both body and spines ; the others are all free, though whether in 
aged individuals this condition continues, is a matter of doubt. It is probable, from the generally 
abnormal condition of the cervical vertebrae in the Cetacea, that comparatively wide variations in 
the amount of ankylosis may obtain in different individuals of the same species, and also in the 
same individual at different ages. The bones in this individual are larger and stronger than in 
D. Bairdii, but the spinal canal is proportionately smaller. The canal of the first spinal nerve, 
which in D. Bairdii is a shallow groove behind the upper edge of the condylar facets, is here (by 
a slender process extending upward and backward from that edge, and coalescing with the anterior 
base of the spinous process) converted into a foramen. The spine is keeled and convex below, 
instead of excavated, and flat, with a very narrow median keel, above. The spine is broader, and 
