THE MOLLUSCS OF THE GREAT AFRICAN LAKES. 161 



closely examined were found to be embryo rufofilosi in all 

 stages of their late development. By pushing a bristle into 

 the pit beneath the eye, on the right where the groove leading 

 from the aperture of the oviduct terminated, it was easy to 

 ascertain that this singular brood-pouch on the left was 

 connected with the base of the groove and the pit on the right 

 by a small tube (PI. 14, fig. 10, c), which passed completely 

 through the foot beneath the buccal mass. Thus the external 

 groove passing forward from the opening of the oviduct, and 

 which unquestionably corresponds with the ciliated spermatic 

 groove in the male, is connected in the female with an 

 invaginated tube aud brood-pouch, and we must consequently 

 regard all these structures as the correlated parts of an 

 accessory reproductive apparatus, which in the complete 

 form just described is not present, so far as I can ascertain, 

 in any of those Prosobranchs the anatomy of which is known. 

 In searching for the meaning of this singular apparatus I 

 discovered by accident among some of the so-called Melanias, 

 which the authorities of the British Museum had courteously 

 placed at my disposal for comparison, an obviously analogous 

 but not quite similar condition of the reproductive apparatus 

 in several of the viviparous females belonging to these forms. 



In the so-called Melania episcopalis (Lea) which I 

 received through Mr. Smith we found, on removing the body- 

 wall, really in order to expose the nerves, that not a little to 

 our surprise we had cut into a sac unconnected with the 

 oesophagus, and which was filled with embryos in all their late 

 stages of development (PI. 14, fig. 13, B. P.). On examining 

 the position of the external opening of the oviduct, it was soon 

 seen that this was put into relation with a subocular pit (PI. 

 14, fig. 13, X.) by a most prominent groove (fig. 13, g. v.), and 

 it was easy to pass a bristle {B.) from the exterior opening of 

 the pit into the brood-pouch which had already been opened 

 up (PL 14, fig. 13,^. P.). 



From this dissection it became at once evident that in M. 

 episcopalis there existed the same relations between the 

 oviduct in the female and an external groove connected with 



