228 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 8, OCTOBER, 1899. 



variety. A small and slender form of it from Guernsey resembles 

 O. diaphana. 



Var. nitida Aid. — Scilly Islands; Skegness. 



Var. glabrata F. & H. — Guernsey; Scilly; Torbay; Bundoran; 

 Iona; Dornoch Frith. 



Var. dubia Jeffr. — Frequently found with the type. There are 

 several forms of it, ranging from a narrow to a broad oval, and the 

 tooth and umbilicus are as variable as in the type. Its permanent 

 characters are a shorter spire and a larger body-whorl, which gives it 

 an oval outline. 



Var. exilis Jeffr. — Jersey; Borough Island; Skegness; Puffin 

 Island; Cumbrae; Arran; Iona. I am not quite satisfied with this 

 variety. It appears to be rare, and resembles var. alba in its propor- 

 tions, but in this the whorls are not spindled, and the suture is 

 shallower. It must not be confused with O. albella var. subcylindrica, 

 which it resembles; that has a slighter tooth and a smaller mouth; 

 nor with a convex form of O. plicata; the latter has a smaller mouth 

 and a sharper apex. 



Among the numerous monstrosities and distortions to which this 

 species is subject may be mentioned one with telescoped whorls, 

 which is the most prevalent; another with scalar or with carinated 

 whorls, a contracted or expanded aperture, a developed pillar lip; a 

 rare one has a double outer lip, and four specimens from as many 

 places have a fully developed canal on the pillar as in the genus 

 Lacuna. 



Jeffreys' figure of the type is perfect; unfortunately he does not 

 figure any of the varieties, but his original figures of var. alba 1 are very 

 good. Forbes and Hanley's figure is a fair one, but too compressed; 

 their var. alba is nothing like; and their var. dubia was figured by 

 error as O. unidentata var. turrita, and is not altogether bad, though 

 the authors say in their Appendix "we do not like the figure;" but 

 their O. glabrata and O. nitida are very good representations of 

 Jeffreys' varieties. Sowerby's type figure is not good; the suture 

 should be deeper, and the length given is too short by one-half; but 

 his figure 18 (indexed as O. lukisi) is nearer the mark; those of vars. 

 alba, nitida, and dubia are perfect; while his figure of var. glabrata is 

 not that form, though figure 15 is. 



O. pallida Mont. — Quasi-parasitic or commensal with various other 

 mollusca. It has long been known in company with Pecten, and I 

 have previously mentioned its association with O. rissdides among 

 Mytilus edulis in South Devon, and with Turritella terebra in the 

 Shetlands. 



1 Ann. Mag. Nat. Hist. (2) vol. 2, p. 337, 1848 ; and (3) vol. 3, p. 113, pi. 3, f. 20a, b, i£ 



