1916.] H. H. Godwin-Austen : Mollusca, VI. 555 



Subfamily DURGELLINAE, God win- Austen, 1888. 



Genus Durgella, Blf, 



Durgella aborense, n. sp. 



(Plate xlvii, figs, i — id). 



Locality. — Upper Rotung, Abor Hills, 7 specimens, No. 5907- 

 13 (S. Kemp). 



Shell (fig. lb) ovately globose, thin, transparent, shining, 

 membranaceous ; sculpture none, very indistinct close lines of 

 growth on the last whorl ; colour very palest ochre, apex white ; 

 spire flatly convex; suture very slightly impressed; whorls 3, 

 rapidly increasing, tumid; aperture widely lunate; peristome 

 thin, membranaceous ; columella margin oblique, not thickened. 



Size : maj. diam. 70, alt. axis 30 mm. 



This is " Gastropod D ", 7— 8-i-i2, of Mr. Stanley Kemp des- 

 cribed by him as follows : " Common under leaf stems of plan- 

 tain. Shell largely covered by mantle-lobes when the animal is 

 fully extended. Anterior part of foot very pale and semitranslu- 

 cent with two broad dorsal dark grey stripes which are continued 

 to the base of the eyestalks. Eyestalks entirely dark grey. Hind 

 part of foot pale brown and semitranslucent, sometimes flecked 

 with white. Mantle-lobes pale brown with flecks of white and red 

 brown, with minute pimples. Body in shell horn-coloured with 

 black marbling. Sole of foot pale and translucent, its dorso- 

 lateral margins with small white flecks. This snail, when dis- 

 turbed, withdraws the anterior part of its body into the shell and 

 lashes about with the posterior part which it extends to an unusual 

 length, twisting, turning and jumping by this means." 



The animal (pi. xlvii, figs, i, la) preserved in spirit is about 

 22 mm. in length, pale in colour throughout, two grey stripes on 

 neck extend to the eye-tentacles. The living animal is well des- 

 cribed above by Mr. Kemp. The foot is narrow, well divided, 

 indistinctly segmented, the mucous gland has a conspicuous long 

 overhanging lobe ; the right and left shell lobes, which are both 

 ample, are much contracted and the edges rolled in, as shown in 

 the drawing, but it is easy to imagine how they would spread over 

 the shell in life from the mantle edge, the dorsal lobes are not so 

 affected, and the left is narrow and long. The peripodial margin 

 is broad, and the side of the foot above it well segmented. 



In the genitalia (fig. ic), the male organ consists of a long 

 sheath tapering upwards to the bend at the retractor muscle, the 

 epiphallus is very long, the spermatheca short, wide at base, 

 tapering to a blunt point. There is no amatorial organ and it is 

 therefore interesting to compare this with the same organs in 

 Durgella assamica, G.-A., Moll. Ind., plate Ixxvii, fig. 6. In 

 Durgella christianoe and rogersi of the Andaman Islands, and in 

 Durgella dekhanensis of Southern India, the amatorial organ is also 

 absent. 



