232 Records of the Indian Musemn. [Vol XXII. 



enclosed in a small pocket (zv'rfc Baudelot, 1863, p. 218, pi. v, 

 figs. 14-15)- 



(5 . The testis in Vivipara bengalensis forms a compact semi- 

 lunar organ h'ing on the right of the branchial chamber, and 

 occupying the same position as the uterus in the female. It is 

 of a bright orange-red colour and extends to the upper end of 

 the branchial cavity, where its apex is in close relationship with 

 the pericardial cavity and is connected by a thin fold of memb- 

 rane with the lower surface of the liver. The gland is flattened 

 from side to side, the light surface being in contact widi the shell 

 while the left surface forms in part the right wall of the ureter 

 and below this the right wall of the mantle cavit}'. In possessing 

 a testis formed of a single mass in this position in the body 

 Vivipara bengalensis differs markedh' from Vivipara vivipara, in 

 which the testis consists of two distinct portions, the upper 

 occupying the extreme apex of the visceral hump and the lower 

 lying at the lower margin of the liver between the stomach and 

 the coil of the intestine {vide V. .Siebold, 1836, p. 241, and vSimroth, 

 1896-1907, pi. xliii, fig. 9 ; also Erlanger, 1891, pp. 665-666). 



Although the testis in Vivipara dissimilis (Miiller) occupies the 

 same position as in V . bengalensis, it differs in having a more or 

 less quadrilateral extension from its upper pole, which passes 

 upwards on the outer side of the pericardial cavity and abuts 

 against and is firmly united to the lower aspect of the liver, from 

 which, however, it can be readily recognised by its golden orange 

 colour. This upward expansion is clearly demarcated off from the 

 rest of the organ, which closely resembles the whole testis of 

 V. bengalensis. and partakes more of the nature of a second lobe. 

 V, dissimilis in this respect is intermediate between V. viiipara 

 and V. bengalensis. 



A series of narrow delicate ducts, the vasa efferentia, arise 

 from the lower border of the testis and passing respectively up- 

 wards and downwards along its lower border converge to form a 

 narrow tube, the vas deferens, which passes to the left beneath 

 the floor of the branchial chamber, crossing above the sub-intesti- 

 nal nerve, to reach the \'esicula seminalis. The first part of the 

 vas deferens is sometimes dilated to form a spindle-shaped swell- 

 ing, but the portion of the duct near the vesicula seminalis is 

 narrow. The vesicula seminalis forms a wide tube which passes 

 downwards and forwards from just in front of and below the 

 pericardium to the base of the right tentacle beneath the floor of 

 the branchial chamber approximately in the middle line and ex- 

 actly beneath the branchial fold. The upper portion of the organ 

 curves round to the right to meet the vas deferens. The whole 

 organ is pigmented and possesses an iridescent appearance like 

 mother-of-pearl. Cuvier (18 17, p. 7) described this structure in 

 V. vivipara as the copulatory organ, but Treviranus subsequently 

 referied to it as a seminal vesicle, and there seems to be some 

 doubt as regards its true function. Later authors refer to it 

 either as the vesicula seminalis or the prostate gland. Erlanger 



