DTTEGELLA. 



213 



[Subfamily DURGELLIN^. 



Durgellinffi, Godwin- Austeyi, Mol. Ind. i, 1888, p. 253 (typical 



genus Durfjella) ; ii. 1898, p. 60. 



Shell globose or much depressed, thin, often membranaceous. 

 Auimal with ample shell-lobes on both sides, nearly concealing the 

 shell in life. The amatorial organ' is present in some genera, 

 absent in others. The radula is very broad, with a great number 

 of similar, closely-packed, curved teeth on narrow plates, in some 

 species as many as 400-500, either plain or with a pectinate side. 

 Jaw generally thin and weak, stouter in some.] 



Genus DURGELLA. 



Durgella, Blf. A. M. N. H. (3) xi, 1803, p. 81; Godicin- Austen, 

 Jour. Lin'n. Soc, Zool. xv, 1881, p. 291 (anatomy) ; id. Mol. Ind. 

 i, 1883, p. 142 ; ii. 1898, p. 60 ; ii, 1907, p. 205. 



Type. D. levicida, Bs. 



Eanr/e. Probably the greater part of the ludo-Malay Eegion. 



Shell thin, Fi^/-tH«-like, of four whorls, with a large oblique 

 mouth. 



Lobes of the mantle partially covering the shell when expanded, 

 the right shell-lobe being broad and triangular, the left also 

 triangular and reflected over the edge of the shell from near the 

 respiratory orifice. Dorsal lobes moderate. A broad peripodial 

 fringe ; the mucous pore is well developed, with a large overhanging 

 lobe ; sole divided into 3 parts longitudinally. In the generative 

 organs a dart-sac is large and usually present, sometimes absent ; 

 the spermatheca is of moderate size, wide at the base, then con- 

 stricted, and broader again at the end ; there is no distinct kale-sac, 

 though an expansion may be noticed at the junction of the vas 

 deferens. 



The jaw is thin, membranaceous, almost straight on the cutting- 

 edge. The odontopliore is broader than long, \Aith a minute 

 rhachidian tooth, generally unicuspid; the lateral teeth are 

 excessively numerous, there being no broad plates near the 

 middle, but a gradual diminution takes place in size from the 

 innermost to the outermost tooth, all having a serrated curved 

 edge with numerous cusps. 



a. Typical forms from Eastern Himalaya, Assam, and Burma. 



318. Durgella levicula, Bs. (Helix) A. M. N. H. (3) iii, 1859, p. 391 ; 

 Blf A M. y. H. (3) xi. 1863, p. 81 ; id. (Nauina) J. A. S. B. 

 1865, 2, p. 67 ; Pfr. (Helix) Mo?i. Hel. v, 1868, p. 48; H. ^- T. 

 (Helix) C. I. 1876, pi. 90, tigs. 1,4; Godicin-Auden, Jour. Linn. 

 Soc, Zool. XV, 1881, p. 291 (anatomy) ; Nevill (Naniua), Hand-l. 

 i, 1878, p. 26 ; Godmit-Austen, Mol. 2nd. i, 1883, p. 142 ; id. t. c. 

 ii, 1898, p. 61, pi. 76, figs. 1-6 (anatomy). 



Shell subperforate or very narrowly perforate, globosely de- 



