816 



gitudinaliter costatis, costis Isevibus, subobliquis, crassis, interstitiis 

 IsevibuSj in mediis^ unipunctatis ; apertura obliqua, semielliptica, 

 antice producta, subcaualiculata et refiexa; columella^ in medio, 

 plica valida instructa. 



Eemarkable for its subulate form, and styligerous spire formed 

 of transparent, nearly equal, nuclear volutions, the first of which 

 is placed as in Turbonilla. 



Sorsogon, province of Albay, isle of Luzon ; coarse sand, four 

 fathoms. H. C. (Mus, Cuming.) 



13. Pyramidella aclis (pi. clxxii. f. 16, 17), A. Adams^ 

 Pro. Zool. Soc. 1851, July. 



P. testa subulata, alba, nitida; anfractibus octo, planiusculis, 

 longitudinaliter plicatis, plicis sequalibus, subconfertis, interstitiis 

 IsBvibus ; apertura semiovata, labio subincrassato, plica unica mu- 

 nito; labro subdilatato. 



This is a slender, subulate species, somewhat resembling a Ris- 

 soina, and differing from P. metula in the interstices between the 

 longitudinal ribs being smooth, and without elevated lines. 



Pliilippines. (Mus. Cuming.) 



Genus MONOPTYGMA, J. Lea. 



Tongue unarmed ; proboscis retractile ; tentacles subulate, with 

 the eyes sessile at their upper bases ; foot narrow, elongate. 



Operculum horny, subspiral. 



Shell elongated, imperforate, many-whorled, transversely stri- 

 ated ; aperture small, entire in front ; columellar lip with a single 

 obscure winding plait ; outer lip simple, acute. 



Si/n. Menestho, Moller ; Pyramis, Brown ; Monotygma, Gray. 



This genus was founded on a fossil species; it differs from 

 Odostomia in being subulate, and in the columella having an ob- 

 lique plait instead of a transverse tooth. 



1. MoNOPTYGMA STRIATA (pi. clxxii. f. 18), Gray. 



M. testa turrito-subulata, solida, olivaceaj anfractibus planis, 

 transversim sulcatis, sulcis profundis, distantibus; apertura ob- 

 longa, intus alba. 



Subulately turreted, sohd, olivaceous ; whorls flat, transversely 

 sulcate, grooves deep, wide apart ; aperture oblong, white within. 



This species is a very thick and strong shell, with a somewhat 



