C08 MAJOR GODWIN-AUSTEN ON [Nov. 17, 



1. Descriptions of five new Species of Helicida of the Sub- 

 genus Plectopylis, with remarks on all the other known 

 forms. By Major H. H. Godwin- Austen, F.R.G.S., 

 F.Z.S., &c, Deputy Superintendent, Topographical Sur- 

 vey of India 



[Received September 25, 1874.] 

 (Plates LXXIII. & LXXIV.) 



The new species here described are from a collection of shells made 

 in the Naga Hills and Munipur, when I was employed on the survey 

 of that part of the country, which has proved so rich in Molluscan 

 fauna. 



Plectopylis was established as a good and distinct subgenus of the 

 Helicidse by Mr. "W. H. Benson, in the * Annals & Magazine of Na- 

 tural History' for April 1860. I have been led to give drawings 

 of all the species I could obtain, in order to better elucidate the in- 

 teresting change that has taken place in the form of the internal bar* 

 riers, and which on the examination of many specimens of local spe* 

 cies I have found most constant. 



Benson's excellent paper leaves very little to be added ; but I trust 

 the drawings now given may be useful not only as illustrative of the 

 new species but of his paper and the forms he described, as well as 

 those afterwards collected by Mr. "W. T. Blanford, and described by 

 him in the Journ. Asiat. Soc. Beng.* 



The subgenus arranged under its principal physiological characters, 

 as given in the table annexed, presents two well-marked divisions, the 

 first of which can be further subdivided into two, and the second 

 into three subgroups. 



Helix (Plectopylis) serica, nov. sp. (Plate LXXIII. fig, 5.) 



Shell dextral, very openly umbilicated, discoid, pale horny brown, 

 very flat above, with regular narrow oblique bands of brown crossing 

 the whorls. Epidermis thin. The apex very slightly higher than 

 the adjacent and outer whorls. Whorls 7, narrow and closely wound, 

 flat above, the last descending near the aperture, which is diagonal ; 

 outer margin circular ; peristome white, reflected, continuous on the 

 body- whorl or parietal margin. The palatal teeth, 6 in number, are 

 situated rather more than one third the circumference from the aper- 

 ture ; and, counting from above downwards, the first is very minute, 

 the 4th, 5th, and 6th the largest. On the parietal side of the whorl 

 there is one single vertical lamina with short bifurcations or supports 

 above and below, 



Major diam. 0'50 inch, minor diam. 0'43, alt. axis 0*16. 



Hab. I first collected this shell on the peak of Henozdan, Burrail 



* ' Contributions to Indian Malacology,' No. V. vol. xxxiv. part ii. pp. 8, 9. 

 } 'ide also notes by same on a species of Tkctopylis, ' Ann. & Mag. Nat. Hist.' for 

 April 1861, ser. 3, vol. xi. p. 86. 



