288 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



the hinder end of the buccal mass. The odontophoral support is 

 composed of radial fibres possessing elongated nuclei, with polygonal 

 cells interspersed between them. 



The oesophagus arises from the middle of the upper surface of the 

 buccal mass, and is rather broad, especially in the region of the 

 salivary glands. These glands are irregular in form, and are united 

 with each other above the oesophagus, except towards their anterior 

 ends. Their ducts, which are not quite so long as usual, open into the 

 cavity of the buccal mass on each side slightly below the opening of 

 the oesophagus. Passing backwards, the oesophagus leads into the 

 long stomach which extends round a single whorl. The intestine 

 arises from the hinder end of the stomach, and runs forwards almost 

 to the posterior end of the pericardium, where it bends upwards and 

 backwards, describing the usual S-shaped curve before passing 

 forwards as the rectum to the anus. The course of the alimentary 

 canal is shown in Fig. 9 on Plate VI. 



The liver is divided as usual into two separate portions. The 

 posterior one occupies the upper whorls beyond the stomach ; the 

 opening of its hepatic duct is shown in the figure. The anterior 

 division lies in the region of the intestine, the loops of which tend 

 to subdivide it into three lobes, one occupying the lower loop, 

 another the upper loop, while the third is chiefly situated behind the 

 upper loop, but has a narrow prolongation which extends forwards 

 above it. 



The Retractor Muscles. — Excepting towards their anterior ends 

 the main retractor muscles are closely coiled in a spiral manner 

 around the columella of the shell. When the muscles are spread out, 

 as shown in Fig. 3 on Plate VI, it is seen that the columellar 

 muscle divides close to its origin into an upper and a lower 

 portion. The latter is the broad retractor of the hinder part 

 of the foot. The upper portion soon divides again into a 

 right and a left branch, and a little further forwards the left 

 branch again divides into an upper and a lower muscle. The 

 upper muscle is the powerful buccal retractor, which becomes 

 subdivided into several strands close to its insertion in the buccal 

 mass. This muscle appears to be innervated by a pair of very 

 slender nerves arising from the cerebral ganglia. The lower left 

 muscle unites with a strand arising from the right branch, and passes 

 forwards, eventually dividing into the upper and lower left 

 tentacular retractors and a couple of muscles to the left side of the 

 anterior end of the foot. The right branch, after giving of! the muscle 

 that unites with the left branch, also passes forwards, and divides 

 into the retractors of the upper and lower right tentacles and of the 

 right side of the anterior end of the foot. These retractors all lie on 

 the left of both the male and female genital ducts. The muscular 

 strand that passes from the right to the left cephalic retractor in 

 front of the origin of the buccal retractor, is not an abnormality, as 



