Sirufltire and Oeionowy of Whales. 4r j 
for being ftretched they contract again very confiderably. There 
is nothing uncommon or particular in the ftructure of the ven- 
tricles, in the valves of the ventricles, or in that of the arteries. 
The general ftru&ure of the arteries refembles that of other 
animals ; and where parts are nearly fimilar, the dijffribu tion is 
likewife fimilar. The aorta forms its ufual curve, and fends 
off the carotid and fubclaviati arteries. 
Animals of this tribe, as has been obferved, have a greater 
proportion of blood than any other known, and there are many 
arteries apparently intended as refervoirs, where a larger quantity 
of arterial blood feemed to be required in a part, and vafcularity 
could not be the only obje&. Thus we find, that the intercoftal 
arteries divide into a vaft number of branches, which run in a 
ferpentine courfe between the pleura, ribs, and their mufcles, 
making a thick fubftance fomewhat fimilar to that formed by the 
fpermatick artery in the Bull. Thofe veffels, every where lining 
the fides of the thorax, pafs in between the ribs near their arti- 
culation, and alfo behind the ligamentous attachment of the ribs, 
and anaftomofe with each other. The medulla fpinalis is fur- 
rounded with a net-work of arteries in the fame manner, more 
efpecially where it comes out from the brain, where a thick fub- 
ftance is formed by their ramifications and convolutions ; and 
thefe vefiels moft probably anaftomofe with thofe of the thorax. 
The fubclavian artery in the Piked Whale, before it paffes 
over the fir ft rib, fends down into the cheft arteries which 
afiift in forming the plexus on the infide of the ribs ; I am not 
certain but the internal mammary arteries contribute to form 
the anterior part of this plexus. The motion of the blood in 
fuch muft be very flow; the ufe of which we do not readily fee. 
The defcending aorta fends off the intercoftals, which are very 
large, and give branches to this plexus ; and when it has reached 
the abdomen, it fends off, as in the quadruped, the different 
Vol. LXXVII. N n a branches 
