44 BLOOMER : ON THE BRITISH SPECIES OF THE GENUS SOLEN, 



portion (PI. iii, figs. 13 and 14, C.Sf.) does not project so far anteriorly, 

 nor does tlie posterior end of the pyloric portion rise so much 

 dorsally. The muscular papilla is more central, and the folds of 

 the stomach are more distinct. (Pi. iii, fig. 13). 



The intestine leaves the pyloric portion more posteriorly, and is 

 joined for some distance to the caecum of the crystalline style by 

 connective tissue. This, however, appears to be subject, in some 

 specimens, to some slight variation where a small portion of the liver 

 interposes between them. The intestine after it has passed round the 

 distal end of the caecum of the crystalline style, assumes a larger 

 number of folds, and in some specimens it presents a very folded 

 condition. (PI. ii, fig. 3). 



Sulen margincdus, Pult. and Don. 



The alimentary canal of S. marriinatus (PI. ii, fig. 4), presents 

 many points of difference when compared with either S. ensis or 

 S. siliqua. 



The mouth (PI. ii, fig. 4, M.) is situated some distance anterior to 

 the stomach, and not ventrally as in the before-mentioned species. 

 The lips formed by the labial palps are directed forwardly (PI. ii, 

 fig. 4, A.L., F.L.). The oesophagus is longer and proceeds poste- 

 riorly to the oesophagael portion of the stomach (PI. iii, figs. 15 

 and 16). The stomach (PI. ii, fig. 4, Sf.) lies in a more posterior 

 position over the distal end of the foot, and whilst retaining the 

 characteristic divisions as described in S. ensis, presents several 

 striking modifications. The muscular wall (Figs. 15 and 16, M.R.O.), 

 dividing the oesophagael from the cardiac portion, is much more 

 developed and very muscular, and projects a considerable distance 

 into the stomach, thus separating the anterior part of these divisions 

 from each other. The caecum of the crystalline style, which is or 

 greater length, leaves the pyloric portion on its ventral surface, curves 

 and passes in an anterior direction near the ventral wall of the pedal 

 cavity. (PI. ii, fig. 4, CO.). 



The intestine (Fig. 4, C.In. and In.) pursues a course similar to 

 that of S. ensis, and is for a long distance jtM'ned with connective 

 tissue to the caecum of the crystalline style, both in going, and in 

 returning along it, and afterwards forms only two or three small folds 

 on the dorsal surface of the caecum, before passing into the rectum. 



The liver surrounds the stomach and oesophagus, but a large part 

 of it is situated ventrally to the stomach, and extending backwards, 

 encloses a portion of the proximal parts of the intestine and caecum 

 of the crystalline style. (PL ii, fig. 4). 



