1921.] N. Annandale & R. B. vS. Sewell : Vivipaya. 225 



A series of small muscle strands, usually three iu 

 number, arise close to the origin of the above muscle and 

 pass forwards and upwards to be inserted into the 

 surface of the radular sac. 



The upper wall of the buccal mass is thin and on cutting 

 through it in the anteroposterior line we get a view of the buccal 

 cavity. In the middle line in front arising from the floor is a 

 stout p3'riform mass the narrow end of which projects upwards 

 and forwards ; this is the odontophore and it can be seen to carry 

 the radula which disappears posteriorly into the radular sac. The 

 radula is a yellowish narrow ribbon, which carries a series of small 

 spinose teeth. These teeth are divided according to their position 

 and dentation into three series. In the middle line is the median 

 row, consisting of a single central tooth, as it is called. The 

 anterior border of this tooth is recurved and is cut into a 

 series of denticles. There is a wide rounded median denticle 

 and five smaller triangular denticles on either side. On each 

 side of the central tooth are a pair of laterals. In both 

 cases we get the rounded median denticle and a series of 

 sDialler triangular or claw-like denticles on each side of it. 



Radular Iccth of P. beiigaleiisis. 



As a rule there are five of these claw-like denticles on either 

 side of the median denticle in each of these teeth, but occasit)nally 

 we find that there are six denticles on the outer side of the second 

 lateral tooth. This variation may occur in a portion of a radula 

 the rest of which shows the normal condition. The marginal 

 tooth is usually curved inwards towards the middle line, and bears 

 on its margin a uniform series of small denticles. In some cases 

 as in the radula figured, there may be a broad sharp extra denticle 

 at the extrenre margin. The radula of Vivifara bengalensis. was 

 figured by Fischer (1887, fig. 499, p. 732), but a comparison of his 

 figure with that given above will render unnecessary any apology 

 for refiguring it here. 



Lying behind and above the odontophore is a transverse fold 

 with a crescentic anterior margin, the median portion of which is 

 somewhat thickened and is shghtly notched. Each lateral wall 

 of the buccal cavity is thick and swollen and contains a carti- 

 laginous mass — the odontophoral cartilage. Each cartilage is 

 roughly oval in shape, the anterior end being somewhat more 

 sharply rounded than the posterior, and is concavo-convex, the 

 concavity being towards the middle line. The lower border is 

 thin and is curved inwards. From the outer aspect a little below 

 and behind the centre of the cartilage numerous muscle-fibres 



