392 



CETACEA. 



example the double innominate trunks, and the left of these has a similar sub- 

 clavian, and long parallel carotids. The outer carotid about its middle sends 

 inwards or mesially a small pharyngeal branch and in the opposite direction a 

 cervical branch, the main vessel itself passing below the hyoid arch. The inner of 

 these parallel carotids, in its way towards the head and at unequal intervals, sends 

 several branchlets towards the middle line of the neck, and itself passes above the 

 hyoid. Besides a left vertebral artery and thyroid axis, a considerably sized and 

 deeply situated branch appears to issue from the subclavian. This left deep 

 cervical, post-thoracic, or superior intercostal, goes to form the rete mirabile lying on 

 the inside of the chest. The chief differences on the right side of this foetus as 

 compared with the preceding adult are its wanting a separate axillary artery derived 

 from the right innominate, the right being, like the left axillary, an offshoot from 

 the subclavian, and the subclavian yielding at its root a branch apparently repre- 

 senting a superficial cervical. 



Compared, therefore, with the vascular distribution in GlobicepJialus, the varia- 

 tions in Orcella seem to be as follows : — 



{a) . The proximity of the two main trunks arising from the aortic arch, these 

 main vessels being wider apart in the Pilot Whale. 



(&). No long " carotis faciahs" (Turner) or median third carotid branch from 

 the right subclavian. 



((?). The deep cervical on the right springing from the innominate in Orcella, 

 whereas it has a carotid origin in Globicephalus. 



The hrain : Its configuration. — Whilst the condition of the carcass of the 

 full-grown animal permitted of many of the organs being fairly examined, such 

 was not the case with the brain. It had become so softened, and its parts so fallen 

 asunder, that it could not be properly examined. Its shape, however, was ascer- 

 tained with tolerable exactitude by means of a cast of the cranial cavity in plaster 

 of Paris. Plate XXX, figs. 4, 5, and 6, represent this cast from an upper, a lateral, 

 and a basal view, half the diameter of the original. 



The measurements of the brain or rather of the interior cranial cast are as 

 undernoted : — 



Inches. 



Greatest antero-posterior length (prominence of frontal lobe to post-cerebellar protuberance) . 5'40 



Greatest breadth (viz., temporo-occipital region) ...... 5'85 



Diameter at the middle of frontal region in front of Sylvian depression . . . 5'40 



Greatest height (fronto-parietal region) ....... 4-00 



Extreme length of each cerebral hemisphere . . . . . . . 4"35 



Cerebellum in antero-posterior diameter, about ....... 2"20 



Cerebellum extreme breadth, about . . . . . . . . 4'10 • 



Vertical height of cerebellum ......... 2-60 



Although the brain was somewhat disintegrated, I was able to determine that 

 it was highly convoluted, like what we find in other Cetaceans. 



Viewed from above (fig. 4), its breadth as compared with its length in the 

 cerebral hemispheres is remarkable, this being in round numbers as 6 is to 4J. 



