MURDOCH : ANATOMY OF ASHMUNELI.A. 8l 



and branches. The venation on the right side and right anterior 

 corner, is much more strongly marked than on the left, in the latter 

 it is minute and widely separated. There is also a small, left, posterior 

 efferent vessel, the branches from which are exceedingly minute, this 

 runs forward following the margin of the pericardium, and enters the 

 auricle at the same point as the greater vessel. On the right of the 

 pericardium is another small vessel, which proceeds from the kidney 

 and apparently enters the auricle with the other vessels ; it appears to 

 be the final channel for the blood received by the kidney, from the 

 several efferent branches which enter its right margin. 



Compared with Helix aspersa, Miill., the above species presents 

 no marked difference in the form of the stomach, track of the intestine, 

 division of the left lobe of the liver and track of the ureter, the efferent 

 vessels proceeding direct to the auricle are also the same. The 

 branching and rebranching of the tributary vessels differ as might be 

 expected, and the venation throughout the left region is strongly 

 marked in H. aspersa. This latter species differs in the kidney being 

 short and subtriangular in shape, it has a length of less than twice its 

 width, only twice the length of the pericardium, and less than half 

 the length of the pulmonary chamber. It has also a large efferent 

 branch with several tributaries, on the left of the great efferent vessel, 

 which unites with the latter close to the pericardium. In A. p)sinido- 

 donta there are no conspicuous branches on the left side, the first is 

 slightly better defined than those immediately following, but its junc- 

 tion with the greater vessel is considerably anterior to the pericardium. 



The arterial system I failed to follow with sufficient exactness to 

 give a detailed description ; the great arteries apparently follow a 

 course similar to those in H. aspey^a ; the nervous system is also, as 

 regards the position and union of the several ganglia, very similar. 



The Free Mii>fdes. — The penis retractor is attached to the diai)hragm, 

 as usual. The right and left bands which supply the foot and tentacles 

 unite posteriorly, but, their junction is anterior to the point where the 

 buccal mass retractor coalesces with them, the latter forms a compara- 

 tively wide, shallow trough, immediately before its attachment to the 

 buccal mass. The right ocular retractor passes between the terminal 

 ducts of the generative organs. 



The Generative Organs (PL vii, figs. 4 — 7). — The penis is short 

 and stout, somewhat abruptly contracted. The epiphallus is a long, 

 slender tube, the vas deferens opening into it a little below the apex. 

 The retractor muscle of the penis has a double attachment, it is 

 inserted in the lower third of the epiphallus, and from there continued 

 free to the penis, to which it unites in the form of a thin sheath. The 



