The Non-Marine MoUusca of Portuguese East Africa. 179 



River to this species. They are identical with a set in the British Museum 

 from the Nyika Range, Nyasaland, which Smith considered might be a 

 variety of boivini, than which, however, they are smaller, with shorter 

 whorls. They are very distinctly, though bluntly, angled at the periphery 

 when not quite mature, in which feature they appear to differ from Ps. 

 Jcidetensis (Smith) and typical gibbonsi, while of a more obese contour than 

 the former and with slightly more convex, gradate whorls than the latter. 

 They are of smaller, slightly more slender form than emini Smith, while 

 the whorls increase a little more slowly than in lasti Smith, their paries 

 thus being more horizontal. Further series of all these so-called species 

 are desirable before their exact inter-relationship can be determined. 



Genus Homorus Albers, 1850. 

 Homorus manueli Preston, 1910. 



1910. Homorus manueli Prest., Proc. Mai. Soc. ix, p. 54. D.F. 



Hab. L. Marques. Mtisherra R. Valley ; Zangwe Basin (Cressy) ; 

 Maforga Siding (Mcdowell). 



A dark brown shell with rather broad apex, originally described from 

 Angola. 



Genus Subuliniscus Pilsbry, 1919. 



Subuliniscus chiradzuluensis (Smith), 1899. 



(Plate V, figs. 9-16.) 



1899. Subulina ckiradzuluensis Smith, P.Z.S., p. 588, pi. 33, fig. 44. D.F. 



Hab. L. Marques. District north of Macequece (Cressy). 



The local race is noticeably more obese than the type set from Mt. 

 Chiradzulu, Nyasaland, two average examples measuring 19-8 X 5-8 and 

 17-5 X 5-7, as against 19-2 X 5-1 and 15-3 X 5-0 mm., respectively, but the 

 volution and sculpture appear identical, so there seems to be no reason for 

 regarding them as distinct. 



The animal is viviparous, and the anatomy differs in several respects 

 from that characteristic of the genus Subulina, as will be seen from the follow- 

 ing description. Possibly Subuliniscus may prove to be more nearly related 

 to the genus Bocageia. 



i External features of the animal. — The foot-sole is undivided, and the hind 

 end of the foot is pointed. There is no caudal mucous pore, but a peripodial 

 groove is present, cutting ofE a rather narrow foot-fringe (PI. V, fig. 13). 

 The usual pair of dorsal grooves runs along the neck, but there is no median 

 posterior groove or keel. 



The animal is of a pale colour, except that rather small, irregular patches 



