CRYPTOSOMA. 211 



forms of Helicarionince ; rhachidian tooth broad, with a small basal 

 cusp on each side; inner laterals usually bicuspid, with the cusps 

 on the outer side far from the apex ; outer laterals with two 

 subequal terminal cusps. This is scarcely worth generic rank, 

 but the typical forms are easily recognized. The outer teeth in 

 the radula differ considerably from those of Cryptaustenia and 

 Austenia, and approach in character those of Girasia. 



314, Cryptosoma prsestans, Gould (Vitrina), Bost. Jour. N. H. iv, 



1843, p. 456, pi. 24, fig. 2 ; Pfr. (Vitrina) Mm. Hel ii, 1848, 

 p. 497 ; Theob. J. A. S. B. xxvi, 1857, p. 252 ; H. $ T. (Vitrina) 

 C. I. 1876, pi. 65, figs. 5, 6 ; Nevill, Helicarion (Cryptosoma), 

 J. A. S. B. xlvi, 1877, 2, p. 25; id. Hand-l. i, 1878, p. 14; 

 Godwin-Austen, Mol. 2nd. i, 1882, p. 14, pi. 4. 

 Austenia ? khyoungensis, Godwin-Austen, P. Z. S. 1888, p. 241. 



Shell depressedly globose, rather solid, translucent, covered 

 with an epidermis, having when fresh a resinous lustre, trans- 

 versely striated, without spiral sculpture, pale greenish horny to 

 brownish ; spire very low, convex, apex not exserted, suture 

 almost flat ; whorls 3^, slightly convex above, the last much 

 larger, descending considerably towards the peristome, rounded 

 at the periphery, rather swollen beneath ; aperture very oblique, 

 slightly contracted, almost semioval, breadth exceeding height ; 

 peristome not very thin, upper margin slightly arcuate, columellar 

 curved throughout, receding, and meeting the penultimate whorl 

 almost in a line, at a very open obtuse angle. 



Major diarn. 22, min. 17, height 12 mm. 



ffab. Mergui, Moulmein, Martaban, Tenasserim Valley, Shan 

 States ( Woodtliorpe) ; Sawady and second defile of the Irrawady, 

 Upper Burma (Anderson) ; Upper Siam (Daly}. 



The rows in the radula are about 100 in number, each consisting 

 of about 260 teeth, thus arranged : 120 .2.7.1.7.2. 120 

 (129 . 1 . 129). In the outermost laterals the cusps at the end 

 disappear, and the teeth have blunt almost square terminations, 

 [their form in this case perhaps due to being worn down]. 



The form from the Shan Hills, to which the name Tcliyoungensis 

 was applied, is a little more depressed than the Moulmein shell, 

 measuring 20 x 15^ x 10 mm., but there does not appear to be 

 any other difference. Other specimens from the Shan States are 

 larger and measure 31 x 24 x 15 mm. 



The original type was described as spirally striate. No spiral 

 striation can be found in shells from Moulmein or further north, 

 but there are some subobsolete traces of spiral lines in Siam 

 shells. 



315. Cryptosoma inusitatum, Godwin-Austen, Mol. Ind. ii, 1898, 



p. 51, pi. 70, figs. 1-8. 



Shell depressedly globose, thin, polished, smooth, with indistinct 

 lines of growth, brown in colour ; spire low, convex, apex not 



P2 



