1901.] MOLLUSKS FROM THE PF,RST\>* GULF. 407 



X.B.- — The whole of our material has been carefully examined by 

 Mr. 3. Pace, with whom this difficult genus has been long the 

 special subject of careful study ; and we have in almost every 

 instance followed his opinion. If is mainly by his recommendation 

 that we have ventured to describe certain small, plentiful, but 

 obscure forms, as they have been, perhaps, too hastily considered 

 till now identical with certain forms of the Western Hemisphere, 

 e. g., atrata Gould, ostreicola Sowb., diminuta 0. B. Ad., troglodytes 

 Souv., and ornata Pease. 



Jlsopcs uraxia, sp. u. (Plate XXI II. fig. 9.) 



JE. testa attenuate, fusiformi, angusta, nitida, brunnea, versus 



apicem albescente; aafractibus 6-7, apicalibus tribus Icevissimis, 



vitreis, cceteris obscure sed arete spiraliter striatis, Jcete brunaeis ; 



apertura angasta, oblonga, labro paullulum expanso ; columella 



obliqua, versus basim truncata. 



Varietas albens, nov. 



'1 \sta ouxaiiio albata, aliter uti supra. 



Long. 6-oU, lat. 2 nun. 



Hab. Mekran Coast, in two or three localities, local ; the variety- 

 rarer, found in company with the type. 



A highly interesting mollusc. Judging from the shell alone, it 

 might be considered a GolumbeUa, Euryta, Thala, or even Olivella 

 allied to 0. nympha Ad. & Ang. In consultation with Mr. .Stephen 

 Pace, we decided to allocare it to the genus JEsopus Gould, allied 

 to ColumbJla, aod characterized by its author as possessing a 

 fusiform shell, broadly truncate posteriorly, aperture linear, with 

 posterior callus (this, we may say, does not appear present to 

 any great degree in our specimens) ; columella smooth, vitreous. 



The colour typically is uniformly chestnut or darker brown, 

 fading into white towards the apex — the variety albens being, as 

 aforesaid, wholly colourless ; perhaps, as Mr. Pace opines, a bleached 

 state only. The last two or three whorls are to a great extent 

 vitreous. Aperture narrow ; columella basally truncate, and 

 oblicpie : outer lip inclined to slight effusion. The whole surface 

 of the whorls is closely, but obscurely spirally striate. Mr. Pace 

 adds that he considers Truncaria australis Ang. has affinity 

 with it. 



Fam. Nassij>.e. 



Bl'LLlA (PSEUDOSTROMBUS) CEROPLASTA Melv. 



M.C. Charbar. 7 fathoms, sandy mud, abundant. 



This species might stand as the type of a new subgenus, the 

 character of the longitudinal eostse being distinct from that ob- 

 taining in any other member of the group. 



BULLIA (PSBtTDOBXBOlCBl s) < iminm.wa <>liv. 



P.G. Galig I., at low tide, exhibiting nuuh \ariatiou in colour. 

 Some are pale stramineous, ashy only towards the apex, others 

 banded with dark cinereous on a pale ground. 



