OXYTES. BENSONIA. 1 371 



peristome oblique, acute, but thickened inside, basal and coluniellar 

 margins somewhat reflected. 



Major diam. 37, min. 30, height 22 mm. A more depressed 

 shell measures 34, 29, and 19 mm. 



Hab. Darjeeling, Sikhim, 7000-8000' in forest. 



This species has the shell of Bensonia:, not only is the lip 

 thickened inside, but former lips, produced during periods of rest,, 

 often occur as in B. monticola. In the animal the eye-tentacles 

 are separated by a wide interval at the base. There is no lobe 

 above the mucous gland, which is large. 



Genus BENSONIA. 



Bensonia, Pfr. Mai. Bl. 1855, p. 119 ; Godwin-Austen, Mol. Ind. i, 

 1888, p. 246, pi. 61 (anatomy) ; id. ii, 1901, p. 115, pi. 95 (animal 

 and anatomy). 



Type, B. monticola, Hutt. 



Range. Himalayas from Sikhim to Afghanistan. Some Chinese 

 species are also referred to this genus, but their animals need 

 examination. 



Shell of typical forms perforate, depressed, subdiscoidal, of 

 moderate or large size, thin ; aperture lunate ; peristome thin, but 

 with a thickened callosity inside. In most of the species several 

 lips remain, like varices, at irregular intervals on the whorls. 



The animal of Bensonia monticola generally resembles externally 

 that of Oxytes and Ariophanta, except that there is a broad over- 

 hanging lobe above the mucous pore. Mantle: right dorsal lobe 

 simple, left divided into two ; no right shell-lobe-, left shell-lobe simple* 

 without tongue-shaped process. Generative organs similar to those 

 of Oxytes, with the coiled caecum near retractor muscle ; the dart-sac 

 is large and long, and there is a small pointed kale-sac. The 

 spermatophore is a long, narrow, chitinous ribbon ending in a 

 membranaceous sac with a hard termination. The edge of the 

 ribbon bears bifid spikes. 



The teeth of the radula in B. monticola differ from those of 

 Oxytes and approach those of Macrochlamys in form. The median 

 tooth of each row is strongly tricuspid, the inner laterals, also 

 tricuspid, have an inner cusp near the point and an outer cusp 

 near the base, the inner cusp is soon lost, the outer cusp disappears 

 in about the 36th tooth, and the outer laterals become small 

 and unicuspid, the outermost being very minute ; the formula is : 

 72 . 19 . 1 . 19 . 72. 



According to Hutton, the eggs of B. monticola are about the 

 size of a mustard-seed, oval and greenish white. 



I. Bounded or subangulate at periphery. 



267. Bensonia monticola, Hutton (Nanina), J. A. 8. B. vii, 1, 1838, 

 p. 213 ; H. $ T. C. I. 1876, pi. 52, fig. 3 ; Theob. J.A.S. B. 1878, 

 p. 142; id.ib. 1881, p. 46: Godwin-Austen. Mol, Ind. i, 1888. 

 p. 248. 



