32 BLOOMER : ANATOMY OF CERATISOLEN AND SOLECURTUS. 



The free ixjrtiuus uf the siphon (Fig. 1, In. S\ & Ex. S\) are lung and 

 narrow, and their distal ends turn dorsally. 



The inner parts of the bases of the gills ape joined together as in 5". 

 marginatas. 



Musculature. 



i. The Pallial Muscles. — The muscular bands along the pallial edge pass 

 round the anterior end, and proceed posteriorly as far as the jiuiction of the 

 mantle lobes with the dorsal integument, and close to the part of the latter 

 l)cnctrate<;l by the teeth of the shell (Fig. 1. //.). At the posterior end, 

 where the mantle lobes form the i)ruximal po)tion of the siphon, the walls 

 of the two chambers are more musciUar, and the divisional wall of greater 

 length. 



The antei'ior adductor muscle (Fig. 1, A. A.) is a broad plate of muscles 

 attaining its maximum depth in the posterior part. Anteriorly it curves 

 slightly towards the dorsal siu'facc. 



The posterior adductor muscle (Fig. 1, P. A.) is situated more \n)S- 

 teriorly, and the muscular dorsal integument between it an.d the siphon 

 is consequently shortened. 



ii. The TciJal Muscles. — The muscles of the distal end of the foot are very 

 strongly developed. The retractor j»edis anterior muscles are thick, and 

 do not extend far anteriorly ; while the l)ifurcated parts (Fig. 1, P. H. A., 

 P. U. A.) are also short. When the muscles reach the foot, the fibres pass 

 in a posterior direction under, instead of over, the longitudinal pedal 

 muscles, as in S. inarglnatus. 



The bifurcated parts of the retractor pedis posterior muscles (Fig. 1, 

 P. li. P.) are longer than in .S'. ens is. 



Allmentary Canal. 



The oesophagus (Figs. 2 and o, Ue) is short, proceeds a little distance 

 dorsally ; and curving, passes into the stomach. The stomach is propor- 

 tionately larger than in S. ensis. There are no divisional walls between 

 the oesophagael and cardiac portions (Fig. 2, C. St.), while the pyloric 

 portion (Fig. 2, P. St.) is large, and assumes a more ventral position, having 

 the appearance of being somewhat drawn towards the pedal cavity. The 

 central cavity (Fig. 2, Cai\) is large, and its divisional walls are more 

 marked, particularly on the dorsal and posterior sides. The sac of the 

 crystalline style (Fig. 1, C. C.) leaves the pyloric portion on its ventral 

 side more anteriorly. It goes some distance along the pedal cavity, as 

 in S. marginatus. The intestine (Fig. 1, In.) leaves the stomach, and 

 passes directly along the surface of the sac of the crystalline style (Fig. 

 1, C. C), adhering to it nearly the Avhole of its length, going along the 

 dorsal surface and returning along the ventral one. It then curves round 

 the pyloric portion, and on its dorsal side continues as the rectum (Fig. 1 , 

 E.), the latter runs posteriorly to the cloacal chamber, and terminates 



