468 SANGUIFEROUS SYSTEM. 



organs of the abdomen by two great visceral veins, or poste- 

 rior venae cavae, which enter the two bifurcations of the ante- 

 rior cava near their commencement, and at an obtuse angle 

 calculated to retard the flow of the blood. The visceral vein 

 of the right side is formed chiefly by branches from the right 

 inferior part of the liver, from the intestinal canal, and from 

 the genital organs ; the left visceral vein receives its branches 

 from the left side of the liver, from the stomach, and from 

 the O3sophagus. The great trunks of the two visceral veins 

 are also surrounded with vesicular appendices opening freely 

 into their interior, as the two branches of the cava. 



The two lateral auricles,of a dark grey colour and loose cellu- 

 lar texture, placed at the base of the branchiae, and receiving 

 all the venous blood of the system, are entirely foraminated or 

 deeply pitted on their inner surface, provided with two mitri- 

 form valves at the opening from the sinus venosus, and 

 tapering towards the commencement of the branchial arte- 

 ries, where they are generally provided with minute valves, 

 as in sepia, loligo, and argonauta. In loligopsis, the usual 

 detached venous vesicles are collected into four pyriform 

 clusters placed on the trunk and branches of the anterior 

 cava ; and instead of the usual sinus venosi at the entrance 

 of the branchial auricles, the venae cavae are here surrounded 

 by a spherical cluster of similar vesicles ; and the same 

 spherical clusters of vesicles are observed to surround the 

 four branches of the anterior cava in the nautilus, where the 

 branchial auricles have not been observed, but the usual 

 valves are seen at the commencement of the four branchial 

 arteries. The branchial arteries, two in the naked cephalo- 

 pods and four in nautilus, corresponding with the number of 

 branchiae, follow along the dorsal or fixed margin of the gills 

 between the suspensory ligaments and the pectinated laminae 

 of these organs. The branchial artery of each gill is remark- 

 ably wide and capacious, and gives off two lateral rows of 

 branches which extend ramifying along the inner margins 

 of the branchial laminae. The branchial nerve and the nutri- 

 tious artery and vein of the gill accompany the branchial 

 artery along the free margin of the musculo-ligamentous 

 band which supports the gill. 



The arterialized blood is collected from the branchial la- 

 minae by their peripheral venous branches which unite on 



