010 
MR. H. F. BLANFORD ON THE DESCRIBED FORMS OF TANALIA. 
vary having survived generic and specific differentiation and obtaining to some extent in 
coexistent forms of the same species. 
Reverting to the subject upon which I remarked at the commencement of this paper, 
viz. the endemic character of the land and freshwater molluscan fauna of Southern Ceylon, 
it appears that in the case of Tanalia, as also without doubt in that of Aulopoma (two of the 
peculiar genera), the number of species is really far less than has been represented, that of 
the former genus being (possibly two) probably but one, that of the latter one only. Of 
Plrilopotamis I have met with three species ; and two others have been described by authors, 
but are probably only varieties. Of Cataulus there appear to be five or six and possibly 
more species ; but this genus is not strictly endemic, having a single described representa- 
tive in the Nicobar Islands. Both Philopotamis and Cataulus still require more strict 
investigation than the limited materials at my disposal have enabled me to give them. 
The following is a list of the described species which I have identified as varieties of 
T. aculeota : 
Paludomus loricatus, Reeve, Conch. Icon. 1. 
P. undatus, Reeve, Conch. Icon. 2. 
P. neritoides, Reeve, Conch. Icon. 3. 
P. Gardneri, Reeve, Conch. Icon. 9. 
P. pictus, Reeve, Conch. Icon. 10. 
P. Tennentii, Reeve, Conch. Icon. 12. 
P . funiculatus , Reeve, Conch. Icon. 13. 
P. erinaceus, Reeve, P.Z.S. 1852, p. 127- 
P. areus, Reeve, P.Z.S. 1852, p. 127. 
P. Layardi, Reeve, P.Z.S. 1852, p. 12/. 
P. dilatatus, Reeve, P.Z.S. 1852, p. 127. 
P. rudis, Reeve, P.Z.S. 1852, p. 127- 
Tanalia Reevei, Layard, Ann. Mag. N. H. 1855, 
vol. xvi. p. 138. 
Tanalia similis, Layard, Ann. Mag. N. EL 1855, 
vol. xvi. p. 138. 
Philopotamis Thwaitesi, Layard, Ann. Mag. N. H. 
1855, vol. xvi. p. 139. 
Paludomus Cumingianus, Dohrn, P.Z.S. 1857? 
P 
124. 
P. distinguendus, Dohrn, P.Z.S. 1857, p- I 24 
P. dromedarius, Dohrn, P.Z.S. 1857, p. 124. 
P. nodulosus, Dohrn, P.Z.S. 1857, P- 124. 
P. Skinneri, Dohrn, P.Z.S. 1857, p. 124. 
P. solidus, Dohrn, P.Z.S. 1857, p- 124. 
P. sphtericus, Dohrn, P.Z.S. 1S57, p. 124. 
P. Swainsoni, Dohrn, P.Z.S. 1857, p. 124. 
P. torrenticola, Dohrn, P.Z.S. 1858, p. 536. 
EXPLANATION OE PLATE. 
Plate LX. 
Series I. figs. 1-6. A series of six specimens of Tanalia aculeata, Gmel., to illustrate gradation of 
ornament. 
Series II. figs. 1-6. A series of six specimens of the smooth variety of the same species, to illustrate 
gradation of size, 
oenes III. a. figs. 1-3. A series of three specimens of the smooth variety of the same species. 
Series III. b. figs. 1-3. A similar series of the ribbed variety, to illustrate gradation of the height of 
the 
spire 
The figures are all lithographed from a photograph representing the specimens of their natural size. 
