204 LAND AIv'D FRESHWATER 



Original description : — " Testa sinistrorsa, late umhilicata, or- 

 hiculato-depressa, supe^^ne oblique scabre plicato- striata, liris con- 

 fertis spiralihus, subtus striis obliquis Jlexuosis striisque spiralihus 

 decussata, cornea, epidermide fnsca, scabra (junioris ad carinam 

 priesertim hisjjida) induta ; spira planata, vix elevatiuscula, apice 

 jilanato, sidura leviter impressa ; anfractibus Tg pdanidatis, lente et 

 arete accrescentibus, idtimo antice breviter descendente, superne sub- 

 carinato, subtus valde convexo, circa umbilicum profunduvi, perspec- 

 tivum, conicum, compressiusculo ; ap>ertura valde obViqua, lunari, 

 peristomate expansiusculo, rejiexo, albido, marginibus callo brevi, 

 laminan, elevatiuscula, sinuato junctis. 



" Diam. major 14, minor 12^, axis 4, mill. 



" Habitat raro in regione Sikkim in vallc llungun [Rungnu] 

 (4('00 ped.), necnon prope Pankabari (1000 ped. alt.). 



" Nearlj' allied to II. plectostoma, B., and inhabiting a tract in the 

 vicinity of Darjiling in company with that shell. Much larger 

 than the largest Khasia varie^ty of this species, it is distinguished 

 b)' its much wider conical umbilicus, its depressed planulate spire, 

 planate whorls, closer and more conspicuous spiral striae on the 

 under side, and by the compression of the base round the 

 umbilicus. 



" As is the case in the Khasia Hills, there are two varieties of 

 H. plectostoma in size ; but the largest of the Darjiling specimens 

 does not equal in volume the small Khasia one which formed the 

 type of my original description. Fresh Khasia specimens are 

 furnished with a scabrous hispid epidermis, as well as the 

 Darjiling varieties." 



Locality of specimen dissected. Damsatig. It also occurred on 

 Eissom Peak, and apparently is not a rare shell. 



Generative organs. The penis (Plate CXIV. fig. 2«) is simple, like 

 that of Corilla, but very short in comparison with the great length 

 of the rest of the genitalia and other organs occupying the closely- 

 wound many-whorled shell. The vagina soon develops into the 

 thin-walled oviduct, which was found occupied by about a dozen 

 embryonic shells (fig. 2 b) in various stages of development, the 

 anterior ones, very well grown, showed the coiled visceral sac, and 

 were covered with minute calcareous granules. The spermatheca 

 was a thin cord with a sac-like expansion at the free end. The 

 hermaphrodite-duct ( fig. 2 b) was long, convolute, and lying attached 

 to the side of the albumen-gland. 



The intestine (fig. 2 b) was long and cord-like, the salivary 

 glands small and elongate. The heart (fig. 2) is situated one whole 

 whorl behind the aperture, and lies below the oval-shaped kidney. 

 The oviduct is packed close to the heart. 



The jaw (fig. 2 c) is very thin and delicate, composed of 24 

 elongate plates which slijihtly overlaj) ; the central jdates are the 

 largest. Tlicse plates are attached to a mass of muscular tissue, or, 

 in other words, this muscular tissue merges into the more solid 

 plates ; in this respect there is a similarity to the jaw of Succinea ; 



