OFTHEHEART, VESSELS A. CIRCUL. &c- ig? 



3^ I fhall therefore give a particular defcription of thc 

 circiilating venTcl^of the Ikate, with which I have found the 

 pifces of Liiinaeus agree in every material circumftauce ; and 

 I f hali begin wita the branchial artery^ 



Secl L 



4. At the beginning of ihe branchial artery there arc thrce 

 femihinar valver (^), the middlc parts of which analogous to 

 the Corpufcula Morgagni, are much thicker than in man, and 

 iHuftrate the ufe of thefe organs in him , as they very evident- 

 ly afllfl in preventing the return of the blood when the arte- 

 ly is in adlion. Between thefe valves and the principal cavity 

 of the ventricle in the flcate, there is a cijlindrical canal interpo- 

 fed (f ), the coats of which have the fame mufcular texture as 

 the ventricle itfelf; and their contradion co-operating withthat 

 of the ventricle, we are thence Itd, more^vidently than in 

 man, to perceive the analogy betweenthe (Irudliire of the arte- 

 ries and that of ihe heart. 



5. The coronary arteries of the heart do not take theic 

 rife from the hranchial artery , which like the pulmonary ia 

 xiian, is fpent entirely on their lungs or gills, by ^vq pairs of 

 great branches in the Ikate, and by four in the pifces of Lin- 

 naeus (^). 



6. When we take a fuperficial view of the fmall bulk of 

 the gills ; when we rcfled , that an organ for refloring mo- 

 nientum to the blood fimilar to the left ventricle of our heart, 

 is wanting in fishes; and when fiirther we confider the extra- 

 ordinary ilze of the red particles of their blood ; we might be 

 tempted, at firfl fight, to fuppofe, that their branchial arte- 

 ry dit not divide into very minute branchcs , or that it refem- 



' bled 



(/?) See Tab. IL 42. 



(c) Sec Tab. L fig. 4. 



(d) Tab. L fig. 4. and Tab. XXVL fig. i. 



Artedi Pbihfo^bla, ' ' A.a 



