610 



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 moUuscan 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 

 Fhilopotamis I have met with three species ; and two others have been described by authors, 

 but are probably only varieties. Of Catmdus 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 FJdlojJotamis and Catmdus 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. aculeata : — 



Tanalia similis, Layard, Ann. Mag. N. H. 1855, 



vol. xvi. p. 1.38. 

 Philopotamis Tliivaitesi, Layard, Ann. Mag. N. H. 



1855, vol. xvi. p. 139. 

 Paludomus Cuming'ianus, Dohrn, P.Z.S. 1857, 



p. 124. 

 P. distinguendus, Dohrn, P.Z.S. 1857, P- 124. 

 P. dromedarius, Dohrn, P.Z.S. 1857, p. 124. 

 P. nodulosus, Dohrn, P.Z.S. 1857, p. 124. 

 P. Skimeri, Dohrn, P.Z.S. 1857, P- 124. 

 P. solidus, Dohrn, P.Z.S. 1857, p. 124. 

 P. sphcericus, Dohrn, P.Z.S. 1857, p. 124. 

 1855, P. Swainsoni, Dohrn, P.Z.S. 1857, P- 124. 

 I P. torrenticola, Dohrn, P.Z.S. 1858, p. 536. 



Paludomus loricatus, Reeve, Coucli. 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. (Breus, Reeve, P.Z.S. 1852, p. 127. 

 P. Layardi, Reeve, P.Z.S. 1852, p. 127. 

 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. 

 vol. xvi. p. 138. 



EXPLANATION OF 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. 

 Series 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. 



