286 PYRAMIDELLIDiE. 



We have provisionally regarded the O. alhella ''' of 

 British writers (Alder, Cat. Moll. Northiimb. and Durh. 

 p. 51 ; Jeffreys, Ann. Nat. Hist, new ser. vol. ii. p. 338) 

 as a turreted variety of this species, but have given the 

 description in full, since the shell has not yet been described 

 by any British writer. 



It is of an abbreviated turreted figure, extremely thin, 

 of a squalid white or very pale fulvous hue, semitraus- 

 parent, with a slight resinous gloss, and almost smooth, 

 being marked only with some longitudinal scratch-like 

 wrinkles of increase, that are always, however, more or 

 less conspicuous. There are six moderately convex whorls, 

 whose longitudinal increase is rapid ; they taper above, 

 where they are either obtusely subscalar, or swell out at 

 once from the moderately oblique and strongly pronounced, 

 yet not canaliculated, suture ; the penult turn is rather 

 high ; the apex is obtuse. The periphery of the body, 

 which fills two-fifths of the dorsal length, is not at all 

 angulated ; its basal declination is well rounded, but is 

 sometimes much more gradual than at other times, usually, 

 however, it is a little produced at that portion which forms 

 the anterior extremity of the aperture. In adult speci- 

 mens the mouth, which has an acuminated oval contour, 

 occupies from one-third to two-fifths of the total length ; 

 it is a little produced at the base, where it is rounded, yet 

 not very broadly, and is contracted above by the swell of 

 the preceding volution. The outer lip is convex above, 

 and arcuated below. The pillar lip is elongated, only 

 moderately curved, very narrowly when at all reflected, 

 and furnished with an obscure retired fold, which is placed 



* Supposed to be the TnrhoniUa ulbella of Lovt'n (Index Moll. Scand. p. 19; 

 Ofversigt Vetensk. Akad. Forhaiidl. 1846, pi. 1, f. 11), Lut the identification is 

 not positive. 



