Reference List of South African Non-marie Mollusca. 65 
very slight peculiarities of form, sculpture, or dentition. However, 
in the recently described FH. johannesburgensis, M. and P., it will be 
found that, while the form and sculpture change but little, the 
presence or complete absence of the basal tooth, even among shells 
from under the same stone, is a matter of indifference ; while in 
E. xysila, M. and P., though the dentition remains practically 
unchanged, the length of full-grown specimens varies from 5 to 
8 mm., and the sculpture is sometimes almost lirate, sometimes 
almost invisible, quite irrespective of the size of the shell. 
It can be easily understood, therefore, that, in more widely distri- 
buted species, the range of variation increases with the extended 
geographical distribution; but in many such cases intermediate 
varieties are found in intermediate localities, which link up a 
complete chain of connection between comparative extremes 
of form. 
Taking these facts into consideration, it is highly probable that 
many species at present reckoned distinct will, on cules comparison, 
have to be referred to merely varietal rank. 
As no satisfactory method of subdividing the South African 
Enneine has yet been contrived, the subjoined list of species 
is given in alphabetical order, omitting all reference to any sub- 
genera or sections hitherto proposed. 
7. ENNEA ADAMSIANA, Pfeiffer. [S.A.M.] 
1859 Ennea adamsiana, Pfr., Novit. Conch. i.p. 114. pl. 32,f.9-11. Dr 
1859 3 = Mone Hell ty, p. dad. D. 
1885 * 4. Eryon, Man. of Conch. ip. 98.pl. 19 
f.Ga5 “OLE. 
1904 nm >» Wob:, Conch. Cab: p. 192. pli245 8.8. Di. 
Type in British Museum. 
Hab. Natau. Port Natal (in coll. Pfeiffer). Widely distributed. 
CarE oF Goop Horr. “Said to be found at Korsten, Port Eliza- 
beth” (Crawford). 
var. IMPERVIA, Mely. & Pons. (S.A.M.] 
1896 Ennea impervia, M. & P., A.M.N.H. xviii. p. 315. pl. 16,f.1. DF’. 
1904 r »  Kob.,Conch.Cab.p.233.p1.32,f.21. DF. 
Type in British Museum. 
Hab. Narvat (fide M. & P.). Lower Umkomaas; Equeefa; Port 
Shepstone (Burnup). 
APE OF Goop Hors. Port St. John’s (Shortridge). 
