igiQ-] N. Annandale & B. Prashad : Fauna of Yunnan. 415 



The radulae of Fenouilia and Parapyrgula are very similar in 

 general structure. They differ from those of all Melaniidae, Pleuro- 

 ceratidae, Rissoidae or Hydrobiidae we have examined or seen 

 figured (except the (?) Hydrobiid Delavaya, Heude') in that the 

 cusp of the central tooth is a simple elongate plate. This tooth is 

 otherwise like that of the Hydrobiidae and Rissoidae, with latero- 

 basal denticulations as in many genera of these families. The 

 lateral and marginal teeth, however, resemble those of the Ameri- 

 can Pleuroceratidae, especially in the great enlargement of one of the 

 denticulations of the laterals. As a whole the radula of these two 

 Chinese genera is, therefore, intermediate in structure between 

 that of the Hydrobiidae or Rissoidae and that of the American 

 Pleuroceratidae, but it is no more different from the latter than 

 the radulae of some genera of Hydrobiidae are from one another. 

 Fischer * regards the presence or absence of latero-basal denticula- 

 tions on the central tooth as a subfamily character, but this 

 distinction is not accepted by all malacologists. 



When the soft parts of Fenouilia are examined its real diver- 

 gence from the Hydrobiid type becomes apparent. From this 

 type it differs in the shape of its head, in the position of its eyes 

 and above all in the complete absence of a copulatory organ in 

 the male. The distal part of the genital system, especial^ in the 

 male, is also simpler, the intestine is more capacious and the gill- 

 filaments are longer, extending almost completely across the dorsal 

 wall of the branchial chamber. Unfortunately the anatomy of 

 the Pleuroceratidae is imperfectly known, but the absence of a 

 copulatory organ is well established in all the genera that have 

 been examined. We have satisfied ourselves that this organ is 

 also absent in males of Fenouilia diagnosed by a microscopic 

 examination of the gonad. Stimpson's figure of the living Ancu- 

 losa dissifnilis shows clearly that the eyes are situated just behind 

 the cleft between the tentacles and the head, and this is precisely 

 their position in Fenouilia. The latter also differs from all the 

 Hydrobiidae of which we have particulars in that the head is 

 spindle-shaped, with a distinct neck. Whether this is the case in 

 the Pleuroceratidae we have no information. Stimpson states 

 that the only visible difference between the sexes in Anculosa 

 (= Mudalia) is the presence of a groove on the right side of the 

 body of the female between the tentacle and the base of the 

 operculiferous lobe of the foot. We think that we have detected 

 a similar groove in female specimens of Fenouilia, but they are 

 too much contracted to permit a dogmatic statement. 



Of Paraprososlhenia we have examined only dried specimens of 

 P. (Parapyrgula) coggini. So far as we can say, they resemble 

 those of Fenouilia preserved in spirit, but we rely in placing the 



1 Heude, Mem. Hist. Nat. Emp. Chinoix, I, p. 172, pi. xxxlii, figs. 8, 9, 

 10, loa. See also Bavayand fJautzenberg (^orn n. de Conchyl,, l.X, p. 37 : 1912), 

 who regard Delavaya as a subgenus of Pachydrobia and ascribe to it several 

 species from the Mekong. 



"2 Man. Conchyl., p. 724 (1887). 



