378 Transactions. 



Returning to the cephalic aorta, which we traced above as far as 

 the nerve-collar, we find that as it passes between the pedal ganglia it 

 breaks up into a number of large vessels, some of which run forwards 

 on the floor of the body-cavity, supplying the organs and walls of this 

 region, and some pass backwards, supplying the foot (fig. 1). 



Running forwards we have three main arteries — A, B, C (fig. 4). 

 The first of these, A, supplies the ventral wall of the head, penis, and 

 muscles round the mouth. It would appear from Captain Button's figure 

 that the penial artery was mistaken by him for the vas deferens.* 



B, which I term the inferior buccal artery, arises to the left of A, 

 goes directly into the buccal mass on its ventral side, and supplies 

 almost the whole of this organ. To the left of B again is the branch 

 C, which is the largest of the three : very near its origin it bifurcates 

 into right and left branches, the latter corresponding to A of the right 

 side. The right branch runs forwards for a short distance, where it 

 bifurcates, the rami entering the muscular ventral wall of the head. 

 Running backwards from the cephalic aorta at this point are two 

 large arteries, right and left, which disappear among the muscles of the 

 foot (pd.a.). 



Veins. 



The distribution of the veins is illustrated in my previous article 

 (Trans. N.Z. Inst., vol. 43, pi. 28, fig. 7, and pi. 29, fig. 2). 



In the foot and body-walls are numerous large blood-vessels or 

 spaces, and into these, as far as I have been able to make out, most of 

 the blood eventually makes its way. Part of this blood is collected by 

 a large vein which runs vertically up in the left body-wall near the end 

 of the gill ; on reaching the dorsal surface it bifurcates, one branch 

 — posterior renal vein — being distributed to the kidney, and the other — 

 the afferent branchial vein — running round the posterior border of the 

 gill, and distributing blood to the gill-lamellae. 



Near the respiratory orifice it gives off a large branch — the anterior 

 renal vein — which runs between the gill-lamellae on to the kidney close 

 to the renal papilla, a process of which surrounds the vessel between its 

 origin and the kidney. This vessel has been figured lightly, as it lies 

 deeper than the other vessels, and its reference-line has been misplaced 

 in the figure (vol. 43, pi. 28, fig. 7). Connected with the afferent 

 branchial vein along its whole length there are a large number of pallia] 

 vessels. The blood passes from this vein through the gill, where it is 

 aerated, into the efferent branchial vein, which runs round the anterior 

 margin of the gill. This vein returns blood to the auricle partly by a 

 vein, leaving it half-way along the gill and crossing the kidney, from 

 which it receives several small vessels, and partly by the efferent 

 pulmonary vein, which it joins at the right end of the gill. This latter 

 vessel receives blood from the efferent vessels of the lung and enters the 

 auricle together with the efferent vessel crossing the kidney. 



Another large vein receiving blood from the body generally is the 

 afferent pulmonary vein, which emerges from the body-wall just in front 

 of the pericardium, and runs round the anterior margin of the lung, giving 

 rise to the afferent vessels of the lung. The blood passes through these. 

 and reaches the efferent vessels, which carry it to the efferent pulmonary 



Trans. N.Z. Inst,, vol. 15, pi. 17. fig. B, c. 



