1282 Mr. W. H. Benson on new forms of Cyclostomacea. 



presence of an operculum in this species enables me to fix the 

 proper place of its ally, which inhabits a deep valley near Cherra, 

 in the Khassya Hills. 



17. Hydrocena Pyxis, n. s. 



Testa obtecte perforata, ovato- conica, spiraliter sulcata, succinea, 

 translucente, spiram versus rubente ; spira conica, sutura profunda, 

 apice obtuso ; anfractibus 4 convexis, ultimo | totius testse aequante; 

 apertura obliqua, semicirculari, peristomate tenui, acuto, non con- 

 tinue, margine columellari expanso, reflexiusculo. Operculo ? 



Long. 11 diam. \\ mill. 



Hab. ad Thyet-Mio. 



This species inhabits the northern frontier of the province of 

 Pegu, that previously described representing the genus Hydro- 

 cena of Pfeiffer in the southern provinces. The careful exami- 

 nation of masses of byssus and tree mosses, in which my Cherra 

 species, samta, tersa, and Milium, were detected, will probably 

 reveal other Burmese forms. H. Pyxis, although smaller than 

 H. Illex, is more coarsely sulcate, and the furrows on the lower 

 whorl are more distant near the suture than below. 



The large variety of Cyclophorus pernohilis figured by Gould, 

 65 millimeters in the greater diameter, was found sparingly by 

 Mr. Theobald in the Tenasserim valley, associated with a smaller 

 shell having a more angular periphery, considered by him to be 

 merely a variety, and, in the decorticate state in which it has 

 been sent, bearing a considerable resemblance to Pfeiffer's C. ah- 

 hastrinus, a shell assigned to Ceylon. The figures 4 & 5. pi. 23. 

 of the new edition of Chemnitz give a very imperfect idea of the 

 beautiful colouring of the large shell, or of its bright orange 

 peristome. I much doubt the propriety of Pfeiffer^s reference of 

 this shell to Schumacher^s C aurantiacm. A dubious shell, 

 from Thyet-Mio, with closely-set flexuous spiral striae, has much 

 greater pretensions to be considered as that species. 



C. expansus, Pfr., was not uncommon in the Tenasserim 

 valley. 



C.fulguratus, Pfr., was found, of various sizes, from Thyet-Mio 

 to Rangoon, where the species has the following dimensions : — 



Diam. major 39, minor 32, axis 26 mill. 



The colour of the shining orange peristome is very rich. The 

 operculum is thin and horny, the outer volutions being separated 

 by a raised edge, and the inner ones ill-defined. 



Megalomastoma sedilabi^e, Gould, is not among the shells re- 

 ceived, a circumstance the more to be regretted, as my Bornean 

 species, M. Anostoma, has been mistaken for it on the continent, 

 but fails to answer the peculiar character assigned to it by 

 Gould and Mason, viz. the occurrence of a fissure across the 



