372 MESSES. MELYILL AND STA>~DE>* OX [June 18, 



Abgtropeza diyi>'a, sp. n. (Plate XXI. fig. 3.) 



A. testa? characteribus uti supra. Loivj. 650, lat. 1*75 mm., sp. 



maj. 

 Hob. Gulf of Oman: lat. 24° 05' X., long. 57° 35' E. 205 

 fathoms, mud. 



Shell small, fusiform, 10-whorled, three of these being apical, 

 brown, vitreous, small and smooth; the remainder, much impressed 

 suturally and ventricose, are glazed with a peculiar silvery lustre, 

 though by no means nacreous, being uniformly adorned by two 

 keeled spiral rows of close-set and conspicuously noduled gemmae, 

 the rest of the surface being smooth and shining. Body-whorl 

 slightly produced, below the two gemmuled carinae is a strong spiral 

 plain keel, and thence to the base several lirae or stria?. Mouth 

 oval, outer lip a little effuse, thin, and with the columella pro- 

 duced basally. We have not seen the operculum, and, in spite of 

 the benevolent endeavours of the Eev. Prof. H. M. Gwatkin to 

 extract the radula, success has not yet been attained in that 

 respect. 



The substance is peculiar, the thin shell being covered with a 

 porcellanous or vitreous glaze. The basal prolongation of the lip 

 and the columella recall certain Dialce, e. g. D.pagodula A. Ad. from 

 Australia, which species is embellished with a spiral row of nodules ; 

 the whole characters, however, appear to us to differ fundamentally 

 from the one under discussion. 



Again, Crrithiopsis sinon Bayle (Pirenella dathrata A. Ad.), a 

 solid, fair-sized, elaborately sculptured species, bears a resemblance, 

 but only superficial, to the Argyropeza ; the lip characters are 

 Cerithioid, and the anterior canal distinct and short. 



P. Fischer (Man. de Conch. 1887, p. 697 sqq.) places the recent 

 genus Vanesia Ad. (type V. rufofasciata), from Manchuria, in 

 the family Pseudomelaniidae. consisting otherwise wholly of extinct 

 representatives only ; the well-known Eocene Bayania M.-Chalnias 

 is by him merged into a subgenus only of Pseudomelania Pict and 

 Champ. Loxonema Phil., a Palaeozoic fossil, is allied, and has the 

 aperture dilated in front ; whorls convex, strictly flexuose. All 

 the species of this Eamily were or are marine. V. rufofasciata 

 Ad., in the collection of one of us, is melaniform, smooth, excepting 

 for longitudinal striation in the uppermost whorls, banded thrice 

 spirally, and does not seem near our species. 



Certain Melanice, especially of the Section Melanoides, e. g. 

 asperata Lam., dactylvs Lea, &c, seem to possess analogous labial 

 characteristics ; and our species bears, when highly magnified, so 

 great a resemblance to these fluviatile Mollusca as to suggest the 

 possibility of their having a marine representative in the Arabian 

 Sea ; but it would perhaps be best for the present to locate this 

 species as an outlying form of Cerithiida\ or of Litiopida?. 



About thirty examples were dredged in the above given locality, 

 all very similar in size, but only a very few showing the complete 

 characters of the peristome. Immature examples exhibit the 

 columella fairly straight and sharply projecting. 



