from the Persian Gulf, &c. 9 



smooth, not shining, microscopically delicately spirally strio- 

 late, with flattened nuclear whorls and apex, the remaining 

 whorls decidedly ventricose. Body-whorl to some extent 

 prolonged, mouth ovate ; peristome continuous, slightly 

 thickened. 



Obiortio elongella, sp. n. (PL I. fig. 14.) 



0. testa anguste oblonga, parva, alba, delicata ; anfractibus 10, 

 quorum 3 apicales, apice ipso parvo, rufo, lacvi, deinde duobus 

 rufo-tinctis, cseteris albis, apud suturas impressis, multum ventri- 

 cosis, longitudinaliter, simul ac spiraliter, dccussatim ruguloso- 

 liratis ; aportura ovata, peristomate tenui, fere continuo, colu- 

 mella paullum excavata. 



Long. 4, lat. 1*25 mm. 



Hub. Mekran Coast, off Charbar. 



A small elongate shell, narrower but of the same calibre 

 as Styliferina fulva *, Wats., which is placed by Mr. C. 

 Hedley in his genus Obtortio^, in company with Rissoa 

 pyrrhacme {, M. & St., and the lately described 0. vulnerata, 

 Hedley §. It comes nearest to 0. fulva } but is much the 

 same size and contour as 0. vulnerata. 



The type of this genus was described by myself in collabo- 

 ration with Mr. Standen, as has just been observed, as a 

 Rissoa, and subsequently tentatively considered an Alaba ||. 

 Later both Hedley and Dall ^j placed it among the Pyrami- 

 delliche, but the former author, finding the nuclear whorls 

 non-heterostrophe, has again transferred it to the Rissoidaa. 



This interesting species (0. pyrrhacme) I now have in my 

 collection from Mauritius (W. Moss), from the Persian Gulf 

 (Townsend), and Bombay {Abercrombie) , likewise from 

 Bydong Cays (Haddon), and Thursday Island, Torres Straits 

 (A. K. Henri); and it appears to me not to vary at all, ex- 

 cepting a degree in size, from any of these places and to be 

 quite distinct from 0. fulva (Wats.), with which some authors 

 are inclined to associate it. 



* Rep. ' Challenger ' Exped. xv. p. 571, pi. xlii. fig. 5 (1886). 

 t Hedley, Moll, of Funafuti, Mein. Austral. Mus. iii. p. 412, fig. 6 

 (1899). 



\ Joum. Conch, viii. 1896, p. 310, pi. xi. fig. 70. 



§ Proc. Linn. Soc. N.S.W. 1909, xxxiv. p. 439, pi. xl. fig. 52. 



|| Journ. Linn. Soc. Lond., Zool. xxvii. p. 170 (1899). 



11 Dall & Bartsch, Mon. W. Am. Pyramidellid Mollusks, p. 16 (1909). 



