BLOOMER : ON THE BRITISH SPECIES OF THE GENUS SOEEN. 4I 



integument of the foot. On the ventral integument there is only a 

 very slight trace of the muscle connecting the foot with the anterior 

 adductor muscle. 



The arrangement of the muscles of the foot is similar to that in 

 S. ensis, only they are much more powerfully developed, and passing 

 posteriorly, spread out sooner into the muscular network, as noticed in 

 the distal portion of the foot of S. ensis. 



The Alimentary Can.al. 



Solen ensis, L. 



The fore-gut and the greater portion of the mid-gut and liver lie 

 anterior to the viscero-pedal mass, which, in its distal portion, contains 

 the caecum of the crystalline style, and the posterior portion of the 

 left lobe of the liver. 



The mouth (PI. ii, fig. 2, M.) opens externally as a transverse 

 slit of the body integument on its ventral surface. Its situation is ante- 

 rior to the foot, but posterior to the anterior adductor muscle, and 

 between the lips formed by the fusion of the labial palps. The outer 

 palps give rise to the anterior or upper lip, and the inner ones to the 

 posterior or lower lip. (PI. ii, fig. 2, A.L., P.L.). 



The oesophagus (PI. ii, fig. 2, Oe.) is short, slightly curved, and 

 soon widens into the stomach on its anterio-ventral surface. 



The stomach is an irregularly shaped sac, divided into several 

 parts, while the right lateral half differs from the left half. 



For the sake of convenience, it is proposed to use the following 

 terms for the different divisions : oesophagael — for the anterio-ventral 

 portion, cardiac — for the portion dorsal to the oesophagael, and 

 pyloric — for the posterior portion. 



The left oesophagael portion (PI. iii, fig. 6, Oe. St.) is somewhat 

 muscular, with a few slight folds of its walls, and is bordered by a mus- 

 cular ridge (PI. iii, fig. 6, M.R.C.), culminating at the posterio-dorsal 

 edge with a more muscular papilla (PI. iii, figs. 6 and ir, M.P.). 

 From the base of this papilla two other muscular ridges diverge, dividing 

 the remaining portion of the side into three parts. The middle portion 

 occupies a ventro -lateral position, adjoining the oesophagael part, and 

 in a narrow and deep cavity. (PI. iii, fig. 6, Cav.). At its distal 

 end it receives the small bile duct (PI. iii, figs. 6 and 11, Cav.). It 

 is separated from the pyloric portion by the muscular ridge passing 

 ventrally (PL iii, fig. 6, M.R.F.), whereas the ridge running in a dorsal 

 direction (PI. iii, fig. 6, M.R.C.) divides the cardiac from the pyloric 

 portion. The former is a large, deep, pocket-shaped lobe lying dorsal 



