AETEEIAL AND VENOUS SYSTEM OF LOBSTEE. 399 



(1020.) Several large arteries are derived from the above-mentioned 

 simple heart. A considerable trunk (fig. 201, </) goes from its anterior 

 extremity to supply the eyes, antenna?, stomach, and neighbouring 

 organs ; another, the hepatic (i), which is sometimes double, supplies the 

 two lobes of the liver ; a third large vessel (h) supplies the abdominal 

 or caudal region ; and a fourth, the sternal, derived from the posterior 

 apex of the heart, bends down to the ventral aspect of the body, where 

 it divides the posterior division (II) supplying the lower parts of the 

 abdomen, while the anterior and larger division (m) gives off branches 

 to the legs and foot-jaws (n n n n} ; it likewise furnishes other vessels 

 (o o o o), which are distributed through the branchiae. 



(1021.) The venous system is made up of large and delicate sinuses 

 that communicate freely with each other, and receive the blood from 

 all parts of the body. Those of the dorsal region are represented in 

 the opposite page (fig. 203) : a large venous sinus (a) occupies the 

 cephalic region and covers the stomach ; another cavity (6) lies imme- 

 diately above the heart ; and a series of smaller chambers (c c c c) are 

 situated above the muscles of the caudal region. These cavities, not- 

 withstanding their apparent extent, are very shallow, so that, upon a 

 transverse section, their dimensions are by no means so great as a 

 superficial view would indicate. The sinus (6), or that placed imme- 

 diately over the heart, communicates with that viscus by short trunks, 

 the terminations of which in the heart are guarded by valves (fig. 201, 

 ///)> so Disposed as to allow the blood to pass from the sinus into the 

 heart, but prevent its return in an opposite direction. 



Such is the apparatus provided in the Lobster for the circulation of 

 the blood. Our next inquiry must be concerning the course that it 

 pursues during its circuit through the body. 



(1022.) MM. Audouin and Milne-Edwards*, after very minutely 

 examining this subject, came to the conclusion that the heart is purely 

 of a systemic character, being only instrumental in propelling the blood 

 through the body, but having nothing to do with the branchial circula- 

 tion ; they conceived that the circulating fluid, having been collected in 

 the venous sinuses, was brought to the roots of the branchia?, over which 

 it was distributed by venous tubes, and then returned to the heart by 

 vessels, which they call branchio-cardiac, to recommence the same 

 course. The appended figures, however, which are accurately copied from 

 engravings of the Hunterian drawings in the collection of the Eoyal 

 College of Surgeons of England f, would seem to give great reason to 

 doubt the accuracy of the conclusions arrived at by the eminent natu- 

 ralists referred to, and to show that the heart, instead of being purely 



* " Eecherches Anatomiques et Physiologiques sur la Circulation dans les Crus- 

 taceV' Ann. des Sci. Nat. torn. ii. 



t Catalogue of the Physiological Series of Comparative Anatomy contained in the 

 Museum of the Eoyal College of Surgeons of England, vol. ii. 



