KUNGL. SV. VET. AKADEMIENS HANDLINGAR BAND 59. N:0 3. 41 



below its place in the median line and penetrates deeply; its lowest branches pass 

 över to the right side. Into the stomach there also debouch several liver canals, 

 for example one pair into the hinder part. From the rear part of the stomach a 

 short coecai appendage emerges, inclining somewhat to the left. The duodenal part 

 of the intestine is divided into a narrow furrow on the right and a wider one on 

 the left; these two parts join farther down, and the original right furrow, widening 

 by degrees, passes finally into the intestine proper, which describes a turn to the 

 front and the right. Af ter a deflection upwards, the intestine becomes, to some 

 extent, rather dilated; it grows narrower again before arriving at the pericard, which 

 it pierces as well as the heart, as usual, and then runs, as the rectum, to the anal 

 orifice. 



In the young specimen 3 mm in length a verv short rudiment of the coecai 

 appendage appears; immediately to. the right of it a liver canal debouches. The 

 difference was also observed that here the intestinal turn was situated on the left 

 instead of on the right; perhaps this difference is a matter of individual A T ariation. 



The circulatory system (fig. 40). In the adult specimen the anterior aorta 

 sends its dorsal branch forwards on the left side of the stomach. On the left side 

 of the oesophagus it descends into the foot, detaching small vesseis behind the oeso- 

 phagus as well. The descending aorta sends a weak branch to the right side, while 

 the main trunk plunges into the left side of the visceral mäss to the stomach, where 

 it bipartites and surrounds the intestine beneath the coecai appendage. In the young 

 stage the arteria gastrica runs superficially in the body musculature; on the left 

 side, after coming somewhat in front of the intestine, it plunges down in an oblique 

 direction towards the stomach, where it divides as usual. 



The nervous system (fig. 41) is similar to that of other species of Pseudo- 

 chama in having buccal centra separated from the cerebral ganglia. The cerebro- 

 visceral connectives run half-way between the stomach and the outer body vvall. In 

 the adult as well as in the young specimen a median commissure exists between 

 the nerve cords close in front of the pericard. 



The gills. In the young specimen the gills are almost unfolded or at least 

 in the beginning of foldation ; the adult animal has about 30 filaments to form each 

 fold. The descending lamina of the posterior gill is well developed; it is somewhat 

 larger on the left than on the right side in the adult, but in the young specimen 

 the posterior gills are of equal size. The anatomical structure of the gills agrees 

 completely with that of Echinochama arcinella. 



The nephridia (figs. 42 — 435). In the young specimen the nephridia have a sym- 

 metrical position beneath the median rectum, but the right one extends somewhat 

 higher up and outside the rectum. A small space separates both nephridia from each 

 other. From the medio-lateral corners in the undermost end of the pericardium, which is 

 open right to the fundus, the ciliated funnels of the pericardial tubes emerge. The 

 whole of the pericardial tube is uniformly narrow (fig. 43) and much thinner than 

 the outer sac, or about l j& of it in diameter. It debouches into the upper end of 

 the latter without any dilatation. The pericardial tubes have their inner walls di- 



K. Sv. Vet. Akad. Handl. Band 59. N:o 3. 6 



