MKLVILL : ON CTCLOSTIlEMATIDiE AND LIOTIID^. 25 



suturas depressis, deinde ventricosulis, undique sub lente pulcherrime 

 et arctissime cancellatis, cancillis perminutis, apertura rotunda, 

 peristomate tenui. Alt. 'TS, diam. To mm. 



Eah.—Guli of Oman, lat. 24° 58' N., long. 56° 54' E., 156 fathoms. 



A most recherche little species, four-whorled, the two last being 

 somewhat roundly depressed suturally ; the whorl surface, smooth to 

 the naked eye, is really most delicately shagreened with microscopic 

 cancellations. It is of decidedly rare occurrence. 

 18. CrcLosTREMA PLACENS (Mclvill & Standen). PL III, Figs. 6, 6^5. 

 Adeorbis placens, Melvill & Standen: Proc. Zool. Soc, vol. ii (1901), 

 p. 373, pi. xxii, fig. 15. 



Eah.—Gwli of Oman, lat. 24° 55' N., long. 57° 35' E., 205 fathoms ; 

 also lat. 24° 58' N., long. 56° 54' E., 156 fathoms. 



A minute, depressed, umbilicate glassy species, apparently quite 

 smooth, but in the most frequent form, which we therefore take as 

 typical, close microscopical concentric spiral lines occur on the upper 

 portion of the whorls. 



Yar. coMPLANATA, Melvill & Standen (loc. cit., p. 373). 



Sah. — Keshire, Persian Gulf. 



Surface entirely smooth. This occurred but rarely, and may 

 possibly constitute a distinct species. Till fresh material is found, 

 however, it is the prudent course to place it here. 



Subgenus II : LYDIPHNIS.^ nov. 



Testa profunde umbilicata, discoidalis, alba, tenuis, anfractus 4, 

 quorum apicalis parvus, vitreus, cseteri undique concentrice tenuilirati, 

 ultimus rectus, tribus carinis acutissimis prteditus, quorum superior 

 carina extra labrum projecta porrectionem trialatam prsebet. 



Type : Cyclostrema euchilopteron, M. & S. 



19. Cyclostrema euchilopteeon, M. & St. PI. Ill, Figs. 7, la. 

 Cyclostrema eucliiloiHeron, Melvill «& Standen : Ann. & Mag. Nat. Hist., 

 vol. xii (1903), p. 292, pi. xx, fig. 7. 



Eab.—^vM of Oman, lat. 24°58'N., long. 56°54'E., 156 fathoms. 



The squarely -built body -whorl, with three strong keels, most 

 prominently ridged, acutely projecting, and terminating in a tri- 

 angularly winged extension of the upper part of the outer lip, 

 presents, I think, characters that merit subgeneric distinction. In 

 all probability C. Verreauxii^ Fischer,- from California, would come 

 under the same category, subgenerically. 



Subgenus III": DELPHIXOIDEA, Brown.' 



20. Cyclostrema eumares, Melvill. PI. Ill, Figs. 4, Aa. 



Cyclostrema eumares, Melvill: Proc. Malac. Soc, vol. vi (1904), p. 158, 

 pi. X, figs. 1, \a. 



- Gr. AuTj, Si<pdc)) 



* Journ. de Conch., vol. vi (1857), p. 285, pi. x, fig. 13 (as Adeorbis). 

 2 Belphinoidea , Brown, 1827 : lUustr. Conch. Gt. Brit., pi. li. 

 Tubiola, A. Ad. : Proc. Zool. Soc, 1864, p. 71, in parte. 



