ilOLLUSCA OF INDIA. 



413 



Altc-eus umbonalis, Bs. 



Moll. Ind. vol. i. (1886) p. 194, pi. xliv. figs. 2-2 c. 



Akouk-Tourig, Pegu. 



No. 65.06.4.4 Blf. Coll. B.M. Specimen figured taken ofF glass 

 slip. No. 179.06.4.4 Blf. Coll. is a specimen from Thyetmyo, 

 Pegu. 



ALTCJf.TTS vuLCANi, W. Blanford. (Plate CLl. figs, o, 5 a.) 



W. T. Blanford, J. A. S. B. 1863, xxxii. p. 323; Pfeiffer, Mon. 



Pneum. iii. p. 47: Theobald, Cat. Supp. 1876, p. 40; Nevill, 



Hand-list, i. 1878, p. 294. 



Specimen figured No. 49 Blf. Coll., B.M. 



Original description : — " Shell moderately umbilicated, depressly 

 turbinate, thin, translucent, varying in colour from amber to 

 nearly white, rather closely costulated throughout, more strongly 

 on the inflated portion of the last whorl, and very closely ribbed 

 within the umbilicus. Spire conoid, apex blunt, deep rufous ; 

 suture impressed. Whorls 4, rounded, the last moderately 

 swollen at the side, then constricted and swelling again slightly 

 towards the mouth. Constriction smooth ; sutural tube of moderate 

 length, about 2 mm. Aperture oblique, circular ; peristome crenu- 

 lately waved on the outer edge, the lowest crenulation forming a 

 rudimentary channel at the base; peristome double, the inrier 

 alone continuous, both lips somewhat expanded ; operculum thin, 

 horny, distantly multispiral, very concave externally, internally 

 convex and with a prominent central nucleus. 



" Major diam. 4i, minor 3|, alt. 3, diam. ap. 1| mm. 



" Habitat. This 'species abounds on the upper portions of the 

 isolated peak of Puppa, an extinct volcano lying about 40 mijps 

 E.S.E. of the town of Pagan, in the territories of the King of 

 Ava. It is a more globose form than either A. succineus,^ mihi, 

 or A. poh/gonoma, mihi, to which it is allied. The crenulation of 

 the moutli is perhaps more marked than in any other Burmese 

 species." 



I have figured one of Blanford's shells, the costulation at the 

 base of the sutural tube is particularly strong and at first distant, 

 and I would call attention to the well-marked distant fine costu- 

 lation on the smooth part of the whorl anterior to this, the four 

 cost,© behind the peristome are very noticeable. The same species 

 has been collected near Ava; in all the examples I have looked at, 

 the peristome is less crenulated and in two or three is hardly 

 noticeable. The ribbing behind the peristome is quite as strongly 

 developed. 



Two single specimens (No. 50 and 180.06.4.4 Blf. Coll. B.M.), 

 which I have compared with the type-shells, are in the Blanford 

 Collection. No. 50 is the one referred to by him in the J. A. S. 

 Bengal, 1862, p. 136, under A. humilis; Blanford had not theu 

 discovered A. vulcnni and, the shell being imperfect, bleached, 

 and a single specimen, he did not describe it. It is now of much 



