25 



iiiueivates each tentacle, passing up the centre and giving 

 off branches to the sense cells. 



If the mantle lobe of one side, preferably the right 

 (where the adductor muscle is attached much nearer to 

 the hinge line), be reniuved, the general topography of 

 the viscera can be easily made out. The varioiis organs 

 thus exposed are shown in PI. II, fig. 1. The single 

 adductor muscle occupies a fairly central position 

 (fig. 1, A. a., A. .^.), and serves as the su^jport for the 

 greater part of the animal which surrounds it. Against 

 the hinge line is the deeply pigmented, green- black 

 looking gland, the so-called liver, which will be referred 

 to as the digestive gland (fig. 1, Dg.)- The gills {Br. a., 

 Br. d.) are very conspicuous structures, lying between the 

 visceral mass and the mantle and attached to tlie latter 

 on the right side, so that if the mantle were cut away 

 close to the adductor the gills on this side would also be 

 removed. They consist of a long series of orange coloured 

 filaments suspended from a basal lamina. 



The body proper may l)e divided into: -(Ij \ iscero- 

 pedal mass, (2) the pericardium and rectum, and (3) the 

 renal organs. 



The viscero-pedal mass consists of (a) the Digestive 

 Gland which is situated at the posterior and dorsal 

 extremity and encloses the stomach, and (&) a long, 

 flattened, tongue-shaped reproductive portion, of a brown 

 colour over the whole area, or if the gonads are ripe — 

 white for part of its length (the testis), and pink or 

 brilliant scarlet for the rest (the ovary). There is no 

 distinct division between the digestive gland and this 

 latter portion of the viscera, but just where they are 

 contiguous the rudimentary foot (fig. 1, F.) is situated. 

 It is roughly cylindrical in shape; the distal portion, how- 

 ever is sucker-like, with a deep cavity. The foot, it will 



