OF THE HEART; VESSELS A. CIRCUL. &c. :gg 
(3:71 Íhall therefore give a particular defcription of the 
circulating veffels of the fkate, with which I have found the 
pifces of Linnaeus agree in every material circümftance; and 
l (hall begin with the branchial artery, | 
"Sect, T, 
4... At the beginning of the branchial artery there are three. 
- femilunar valves (b), the middle parts of which analogous to 
the Corpufcula Morgagni, are much thicker than ia man, and 
illuftrate the ufe of thefe organs in him,  as.they very evident- 
ly affift in preventing the return of the blood when the arte- 
tyis in aclion,  Detween thefe valves and the priucipal cavity . 
- of the ventricle in the fkate, there is a cy/indrical canal interpo- 
- fed (c), the coats of which have the fame mufcular texture as 
the ventricle itfelf; and their contraction co- operating with that 
of the ventricle, we are thence led, more evidently than in 
. man, to perceive the analogy between the firucture of the arte- 
ties and that of the heart, | 
x 
5$. "Ihe coronary arteries of the heart do not take their 
fife from the bratichial artery, which like the pulmonery in 
man, is fpent entirely on their lungs or gills, by five pairs of 
great branches in the fkate, and by four in the pifces of Lin-. 
- naeus (4). E i 
6. When we take a fuperficial view of the fmall bulk of. 
the gills; svhen we reflect, that an organ for refloring.mo- 
mentum to the blood fimilar to the left ventricle of our heart, 
is wanting in fishes; aud when further we confider the extra- ; 
ordinary fize of the red particles of their blood; we might be 
tempted, at firft fight, to fuppofe, that their branchial artes 
ry dit not divide into very minute branches, or that it refem- 
bled 
EI oC IUOTCHUT 2 DU EE DUE) 
l 1 f i - 

(5) See "Tab. IT. 42. . 
(c) Sec Tab. I. fig. 4. 
(4) Tab. I. fig. 4, and Tab. XXVI. fig. 1. 
Artédi Pbilofopbia, Aa 

