MELVILL : ON CYCLOSTREMATID^ AND LIOTIID.E. 27 



It will be observed that this genus was designated by its author 

 Microthyca on the plate and Microtheca in the text, as usually written, 

 3ut if derived from ju.iKpov, d/jKr/, no doubt the latter is the more correct 

 rendering. 



Genus LEUCORHYNCHIA, Crosse.^ 

 LEcrcoEHYNcniA Crossei, Tryon. 

 Leucorhynchia Crossei, Tryon: Man. Conch., vol. x (1888), p. 106, 

 pi. XXXV, figs. 86», 86^. 



Eah.—i3vi\i of Oman, lat. 24°58'N., long. 56°54'E.. 156 fathoms. 



I cannot separate these specimens from the Singapore species as 

 3ollected by Mr. Archer, and described by the late (i. W. Tryon in 

 1888. The only difference, indeed, between L. Crossei and the typical 

 L. caledonica, Crosse, is the absence of a peripheral angle around the 

 body-whorl of the former. The examples, not at all infrequent in 

 shell-sand from the above locality, are all uniformly white, shining, 

 without any striation or marking whatsoever, perfectly smooth, sub- 

 globose, whorls 3-4, with continuous peristome, thickened basally and 

 produced into a lingual callosity that very nearly closes over the 

 umbilicus. 



Genus MORCHIA, A. Adams.^ 



MoKCHiA MoKELETi, Fisclier. 



Mbrchia Moreleti, Fisch. : Journ. de Conch., 1877, p. 202, pi. x, fig. 1. 



Mab.—(juU of Oman, lat. 24°58'N., long. 56° 54' E., 156 fathoms. 



One of the smallest and most wonderful of sliells. It is well figured 

 by Fischer, and reproduced equally satisfactorily by Tryon (Man. 

 Conch., vol. x, pi. XXXV, figs. 80-82). Only measuring two milli- 

 metres in diameter, it presents a quaint appearance, the shell being 

 depressed, carinated, the keels furnished with a fimbriately crenate 

 redge ; below, the form is like a small Ammonite, the wliole coil being 

 plainly seen in the unusually wide umbilicar region ; the aperture is 

 almost reversed, as in Anodoma. This very probably may be a distinct 

 species ; it is less in diameter by one-third than Fischer's type ; but it 

 is perhaps best at present not to differentiate it further. 



Family LIOTIID^. 

 Genus LIOTIA, Gray.^ 

 Only three species of this family and genus have yet been detected 

 in the Persian Gulf region, and all occur very rarely and locally. 



1. LioTiA ciDARis (Reeve). 



J Belphinula cidaris, Reeve : Conch. Icon., vol. i, pi. v, fig. 27 ; Proc. 

 Zool. Soc, 1843, p. 143. 

 Hah. — Angrias Bank, off coast of Bombay. Collected by Captain 

 W. A. Tindall, of s.s. "Patrick Stewart." 



1 Journ. de Conch., 1867, p. 319. 



^ Ann. & Mas. Nat. Hist., vol. v (I860), p. 301. (Type, M. ohvoluta, A. Adams.) 



2 Synopsis Brit. Mus., 1840; Proc. Zool. fcjoc, 1847, p. 145. 



