148 Dr. J. B. S. Jackson's Dissections of a 
The ascending aorta measured 4 inches to the first branch 
at the arch; no marked dilatation, the circumference on the 
inner surface being 8! inches; parietes 3 lines thick. The 
ductus arteriosus formed a cord 2: inches long, and § of an 
inch in diameter, externally, but the canal remained. open so 
as to allow the passage of an instrument about 1 of an inch 
‘in diameter. The persistence of this opening is quite re- 
markable, even in a cetacean, not having been found in either 
of the three other specimens, except in the dolphin, which 
was foetal. The arch of the aorta gave off three vessels. 
The first, 6 inches in circumference externally, divided at 
once into two branches, one of which was traced in sitü, and 
was found to be the right carotid, the other taking the direc- 
tion of the subclavian; these vessels were of about equal size; 
and it is remarkable that they were so, considering the great 
bulk of the head as compared with the anterior extremities. 
The second vessel arose only half an inch from the first, was 
5 inches in circumference, and consisted almost wholly of 
carotid. The third vessel arose from the aorta 5 inches 
beyond the second, was 3! inches in circumference, and may — 
have been a superior intercostal, such as was afterwards fou 
in the dolphin. vA 
I regret exceedingly not to have seen the intercostal t 
plexuses, one of the most interesting structures in the ceta- — 
ceans, and one of the discoveries of Mr. Hunter which the — 
French have endeavored to appropriate; they were not Over — 
looked, but the first examination was made under too unfavor- : 
able circumstances for observation. d edo 
The vena porta, the vena cavà where it passes behind the - 
liver, and the hepatic veins, are said to be dilated into reser- 
voirs in some of the cetaceans, to be used, like the ples ; 
during the time of submersion; but nothing of the kind wa — 
found in the present case. One singular fact, however, W" — 
I have not seen noticed, was observed in all of the four s E 
mens; and that was, a pel is ence of the umbilical wine 
