292 Messrs. J. C. Melvill and R. Standen on 
The nearest ally is, perhaps, C. eburneum, Nevill (Journ. 
As. Soc. Bengal, xliv. part 2, p. 101, pl. vill. figs. 21, 22), 
which is, however, a larger shell, with coarser sculpture 
proportionately. 
Cyclostrema annellarium*,sp.n. (Pl. XX. fig. 5.) 
C. testa parva, discoidali, profunde umbilicata, supra plana, alba, 
solidula; anfractibus tribus, quorum ultimus magnopere aliis ex- 
superans, rotundatus, undique costis longitudinalibus circularibus, 
numero ad quinque et viginti, preeditus, interstitiis pulchre 
striatis ; apertura rotundata, labro continuo, crassiusculo. 
Alt. 1, diam. 2 mm. 
Hab. Gulf of Oman, lat. 24° 58’ N., long. 56° 54’ E., 
156 fathoms. 
Exceedingly small, but well marked, being deeply um- 
bilicate, flattened above, three-whorled, the last whorl large, 
provided with about twenty-four rounded longitudinal ribs. 
We know no species exactly comparable, C. conicum, Boog 
Watson, being, perhaps, the nearest, from Pernambuco 
(‘ Challenger’ Expedition) ; but this, as its name implies, is 
conical in form. The interstices between the ribs are, as 
in C. conicum, beautifully spirally striate. 
Cyclostrema prominulum, sp.n. (Pl. XX. fic. 6.) 
C. testa depresso-discoidali, delicata, alba, minutissima, profunde 
umbilicata; anfractibus quatuor, quorum duo apicales perleves, 
subvitrei, ceeteris duobus spiraliter undique multiliratis; liris 
levibus, simul ac interstitiis, ultimo permagno, ad peripheriam 
acuticarinato; carina prominente, deinde ad basim lateribus 
obliquis, basi tumidula; apertura rotunda, labro tenui. 
Alt, 1, diam. 2 mm. 
Hab. Gulf of Oman, lat. 24° 58’ N., long. 56° 54’ E., 
156 fathoms. 
A very minute species, deeply umbilicate, white, with the 
surface uniformly multilirate, the lira at the periphery being 
metamorphosed into a strong, very prominent, and acute keel. 
Cyclostrema euchilopteront, sp.n. (Pl. XX. fig. 7.) 
C. testa parva, profunde umbilicata, albo-lactea, subpellucida, tenui, 
nitidiuscula, discoidali; anfractibus quatuor, apicali vitreo, levi, 
* Annellus, a small ring. 
+ ev, xethos, wrépov, from the winged process in connexion with the 
lip. 
