KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 59- NIO 3. 29 



line, embracing between them the blood sinus; behind the ciliated funnels the peri- 

 cardial tube vvidens to an ampulla. Behind the ampullae, which lie close to each 

 other, the tubes again become somewhat narrower, but still lie close side by side 

 until finally they diverge at the uppermost ends of the nephridia at the sides of 

 the interjacent rectum; outside it, on the upper side of the adductor, they widen 

 and are joined, by a curvation upward and forward, to the proximal sacs of the 

 kidneys. The exteriör sacs rapidly widen distally and embrace the pericardial tubes, 

 except on the median side, where these börder upon each other. The outer sacs are 

 strongly and finely lobed and filled with a coarse-grained mäss consisting of entire 

 cells repelled from the walls. Just in front of the ampullae, on the upper side of 

 the ciliated funnels, the exteriör sacs open into each other by a narrow passage. 

 Beneath it they form small lobes on the median side, which soon disappear, a blood 

 sinus filling the remaining space between the ciliated funnels. On the sides of this 

 blood sinus the cerebro-visceral connectives enter into the nephridia, surrounded on 

 all sides by their lobes; between the nerves there project a pair of ventral lobes. 

 The chief outer sac opens laterally close by the nephrostomes through a nephro- 

 proct opposite to and somewhat above the genital pores. 



The quite vestigial foot retractors pass through the nephridia in the form of 

 narrow cords, the strength of which is only about half that of the nerve connectives. 



In the uppermost corners of the pericardium a layer of excretory cells exists, 

 corresponding to a pericardial gland such as is described for Ch. jjellucida by 

 Grieser. 



The circulatory system. Immediately at its origin from the heart, on the 

 dorsal side of the intestine, the anterior aorta is divided into a larger dorsal branch 

 and a smaller descending one. The latter vessel runs along the intestine on its back 

 and left side, branches into the liver beneath the stomach and continues its way 

 to the rear side of the stomach downwards, till finally they disappear near the point 

 where the intestine starts, and are replaced by the intervisceral lacunar system round 

 the intestine and the genital coeca. 



The larger dorsal branch of the anterior aorta runs to the dorsal side of the 

 left body half inside the genital coeca and through the liver, into which it descends 

 and apparently vanishes among the lobes; from the same region, however, it reap- 

 pears more ventrally as the two pedal vessels, and these, farther down, become one, 

 which can be traced into the foot. 



The walls of the aorta are rather thin all över, a feature that is perhaps due 

 to the bad state of preservation. 



The posterior aorta runs along the under side of the intestine with slight 

 asymmetry to the right, and then on its median side behind the adductor. 



As to the afferent blood system, the two branchial veins emerge from the 

 auricles, having from the very outset a considerable width; they give rise to the 

 veins in the branchial axis on the one hand and those along the dorsal and frontal 

 branchial edge on the other; from the latter, in the vicinity of the cephalic ganglia, 

 branches pass över to the anterior adductor and the mantle. 



