426 DR MORRISON WATSON AND MR ALFRED H. YOUNG 
ours. This observer, however, notes a slightly notched condition of the cardiac 
apex which did not exist in our specimen. He makes no reference to the 
coronary sinus or to the openings of the cardiac veins, on which points 
Barciay and NEILu* are equally silent. The latter, indeed, do not appear to 
have examined the heart specially, and give no account whatever of the aorta 
and its branches. 
Cetaceans in general agree with Beluga in possessing a heart characterised by 
its flattened character and capacious auricles. In no species is the substi- 
tution of two venous orifices in the place of a coronary sinus described ; it 
may therefore in all probability be regarded as exceptional in Beluga. 
Dr Jacxsont affirms the existence of a single coronary opening, unprovided 
with any valve, in the spermaceti whale; TurNeR{ notes the presence of 
a coronary sinus, and the absence of any Thebesian valve, in the foetus of 
Balenoptera Sibbaldii; and Burmeister § speaks of the single orifice of the 
nutritive vein in Ziphiorrhynchus cryptodon (Epiodon cryptodon, Gray). 
But, though no remarkable differences are to be found in the hearts of 
the different cetaceans, quite the reverse holds good with respect to the aorta 
and its branches, the differences in arrangement of these vessels being mani- 
fold. In most cetaceans the aorta is large at its commencement, but suddenly 
contracts in the arch—a condition first noticed by Jackson || in Phocena 
globiceps. ‘The number of branches (exclusive of the coronary arteries) given 
off from the arch varies, as does also the arrangement of these. In Beluga 
two innominates, each dividing into a common carotid and a subclavian, are 
the only branches. Amongst the toothed whales two innominate trunks ~ 
seem to be the rule; but in most cases an additional branch, such as a 
deep intercostal or superior thoracic branch, is also to be found springing 
from the arch. In Delphinus phoceena’ the left posterior thoracic occasion- 
ally springs from the arch; usually, however, the latter agrees with that of 
Beluga in simply giving off two innominates. According to Cuvier and 
MECKEL, in the porpoise each of these divides into a common carotid, sub- 
clavian, and vertebral, whilst Srannius,** RATHKE,** Barkow,** and TuRNER** 
maintain that no common carotid exists, and that the external and internal. 
carotid arteries arise separately from the innominate. In Globiocephalus 
Svineval, TurNER 4 describes and figures two innominates and a left posterior 
thoracic as springing from the aortic arch, the external and internal carotids, 
together with the subclavian of each side arising directly from the trunk of 
the innominate artery. <A similar arrangement is noted by Murrett in 
Risso’s Grampus (Grampus Rissoanus). = 
* VIII. p. 380. i; p. 147, + XVII. p. 227, § XLI. p. 96. 
|| IV. p. 164. q IX. p. 66. ** Quoted by Turner, IX. p. 66. ff X. p. 133. 
