96 Mr. W. H. Benson on Clostophis and Rhiostoma. 



A slight pit is discoverable on the outside of the last whorl 

 near the aperture, corresponding with the internal tooth ; but, 

 from its situation and the minuteness of the object, it is difficult 

 precisely to ascertain its nature. 



If Clostophis should eventually prove to be destitute of an 

 operculum, and allied to the Helicidte, it will then form a curious 

 contrast with its northern Burmese neighbour Hypselostoma, in 

 which a tubular termination to the last whorl is exalted verti- 

 cally above the apex of the shell. 



Rhiostoma *, B., nov. gen. 



Testa subdiscoidea, late umbilicata ; anfractus ultimus solutus, late- 

 raliter descendens ; apertura libera, superne incisa, tubulo imper- 

 fecto retroflexo rimam coronante. Operculum breviter cylindri- 

 cum, multispiratum, apice piano, Isevigato, intus profunde ex- 

 cavatum. 



Rhiostoma Haughtoni, B., n. s. 



Testa late umbilicata, convexo-depressa, solidiuscula, oblique scabre 

 striatula, superne castanea, subtus albida, fascia angusta mediana 

 saturatiore, utrinque angulato-marmorata, ornata ; spira depresso- 

 conoidea, apice prominulo obtusiusculo, sutura impressa ; anfrac- 

 tibus 5, convexiusculis, ultimo cylindrico, antice longe soluto, 

 lateraliter descendente, superne carina obtusa a sutura usque ad 

 tubulum marginalem decurrente munito ; apertura libera, obliqua, 

 diagonal!, circulari ; peristomate subduplici, extus incrassato, re- 

 flexiusculo, superne ad sinistram inciso, tubulo imperfecto, antice 

 aperto, sinistrorse erecto, rimam coronante, munito ; umbilico 

 perspective, profundo : operculo testaceo, multispirato, breviter 

 cylindrico, apice planato, Isevigato, anfractibus arete convolutis, 

 marginibus acute carinatis, spatiis intersitis epidermide scabra 

 vestitis ; intus profunde excavato, polito. 



Diam. major 21, minor 11, axis 8 mill. 



Habitat ad cavernam Damatha, non procul ab urbe Moulmein. 



This shell was discovered by Capt. J. C. Haughton, to whom 

 I am indebted for a couple of specimens, one of which was alive. 

 A weathered specimen, from the same source, was previously 

 received from Mr. W. Theobald, junr., who has since forwarded 

 the animal in spirits. I have mislaid my note on the living 

 animal, which came out freely, but was in a languid condition. 

 From the remains of the mollusk in the other shell, I procured 

 two elongated-triangular, testaceous plates, somewhat convex 

 on one side and concave on the other, and irregularly toothed 

 or jagged on the longest and shortest sides. 



Mr. Theobald was disposed to place his first specimen in the 



* 'Plov, a promontory. 



