BATHYDORIS. 



15 



pharynx, not beneath it. No trace of eyes or auditory organs could be found. The 

 buccal mass is large (18 mm. x 15 mm.) and very strong. The front of it is formed 

 by a thick muscular pad which lies over the jaws. These latter form a disc measuring 

 about 14 mm. x 13 mm. as they lie together. The edges are rather membranous 

 and yellow ; the rest strong and deep brown. They are covered and united by strong 

 membranes, and it would seem that they have no exposed cutting edge, but must act as 

 a powerful prehensile organ. 



The radula is set on a thick, tough, white membrane, from which the teeth are 

 detachable only with difficulty. It consists of 37 rows, deep mahogany colour in 

 front but rather lighter behind, which are unusually bent and curve upwards and 

 outwards. In the longest rows there are as many as 65 teeth on either side of the 



PIG. l3.Bathydoris hodgsoni THREE RHACHIDIAN TEETH, a, b, c. 

 FIG. 14. Bathydoris hodgsoni PIBST LATERAL TOOTH, d. 



FIG. 15. Bathydoris liodgsoni SECOND (e), AND THIRD (/), LATERALS. 

 FIG. 16. Bathydoris hodgsoni LATERALS (g and h) PROM THE MIDDLE OF THE HALF Bow SEEN FROM THE SIDE ; 



THE OTHER TEETH ARE SEEN FROM ABOVE. 



rhachis. The ordinary laterals (Fig. 16) are spike-like and little bent. The base is 

 deeply excavated and often jagged and there is a slight wing-like expansion at the 

 side of the shaft. The fifth lateral from the rhachis begins to be flatter, lower and 

 broader. These features increase markedly in the following teeth (Fig. 15), and the 

 first lateral almost develops an accessory denticle (Fig. 16). The rhachidian tooth 

 (Fig. 13) consists of a plate-like base rather broader behind than in front, and bearing 

 a raised cusp of very irregular shape with several projections and indentations which 

 are not sufficiently symmetrical to be called denticles. The 10-12 outermost laterals 

 decrease rapidly in size, and the last two or three are rudimentary. 



The ossophagus is about 7 mm. wide on issuing from the buccal mass. After 

 dilating a little to form the first stomach the digestive tract turns sharply to the left 



Y 2 



