MOLLUSCA OF INDIA. 15 
so unlike the other species of Helicarion, with which it has been 
classed by other conchologists since; even Mr. Theobald himself, 
in his ‘Catalogue of the Land and Freshwater Shells of British 
India,’ puts it in his section E of Helicarion. H. ovatus, H. Blanford, 
and succineus, Reeve, are also included in this section, but on no 
tangible grounds. 
Geoffrey Nevill, in his “ List of the Mollusca brought back by 
Dr. J. Anderson from Yunnan and Upper Burmah,” J. A. 8. Bengal, 
part 2, 1877, p. 25, recognizes the genus Cryptosoma with these 
remarks :— 
‘The entire shell is covered with a thick and compact epidermis ; 
the largest specimen in the Museum (Calcutta), from Tenasserim, 
measures, axis 27}, diam. 313 mil. It is an extremely abundant 
species in Tenasserim and also near Moulmein; Dr. Anderson found 
it abundant at Sawady and on the banks of the Irrawady, Second 
Defile.” The shell, with animal, was also figured in Dr. Anderson’s 
work from a drawing made, under Dr. Ferd. Stoliczka’s superinten- 
dence, by a native artist, and which I give a copy from the same 
original excellent drawing (Plate IV. fig. 1). 
Vitrina prestans, from Tavoy (Gould), P. Bost. Soc. N. H. vol. i. 
p. 140, read Sept. 6 (1843). 
Vitrina prestans, Gould, Boston J. Nat. Hist. vol. iv. p. 456, 
plate 24. f. 2, read Sept. 6 (1843); Pfeif. Mon. Helic. vol. ii. p. 497 
(1848); Reeve, Conch. Icon. Vitrina, f. 12 (May 1862); Theobald 
and Hanley, Conchologia Indica, plate Ixv. figs. 5, 6 (1870), with re- 
mark “our fig. 6 is scarcely round enough.” 
Cryptosoma preestans, Maulmain, Martaban, and Tenasserim valley 
(W. Theobald), J. A. 8. B. p. 252 (1857). 
Helicarion (Section E) prestans, Theobald, Cat. Land and Fresh- 
water Shells of British India (1876). 
Helicarion (Cryptosoma) prestans, Nevill, J. A. 8. B. part ii. p. 25 
USL). 
Helicarion prestans, G. Nevill, Hand-list of Mollusca in Ind. 
Mus., Calcutta (1878). 
Original description :—“ Testa depressa, fragili, nitida, straminea ; 
anfr. tribus, striis incremente, et volventibus retrculatis ; apertura sub- 
coarctata.” 
The colour is dark straw-colour or amber-colour, inclining to 
green. A thin layer of enamel unites the two extremities of the 
lip. The figure given is very good. 
In response to a wish I expressed in a paper in the Linnean 
Society last year, Mr. Theobald most kindly sent me quite lately a 
couple of specimens, preserved in glycerine, of this species from 
Maulmain. I am now able to give a somewhat more detailed account 
of its forms and anatomy, which gives it a more substantial position 
as a subgenus by itself, and which must, with our present know- 
ledge, be recognized. 
Animal (Plate IV. fig. 2). With tentacles rather short and blunt, 
the extremity of foot truncate, the mucous pore large, but with no 
