MARSHALL : ADDITIONS TO " BRITISH CONCHOLOGY." 289 



be found touching closely on O. insculpta on the one hand, and O. 

 obliqua on the other ; but the apex and sculpture are always uniform 

 and distinct. Though usually having an umbilicus at every stage of 

 growth, I have a few examples without that character. A globular 

 form from Torbay corresponds to O. diaphana var. inflaia, while a 

 monstrosity from Jersey has the whorls obtusely carinated, and in 

 another from the West of Ireland the whorls are compressed ; other- 

 wise monstrosities are rare. The var. intermedia has the last whorl 

 longer, and the whorls are not so turreted ; it can easily be mistaken 

 for O. obliqua superficially, the proportions and outline being the same; 

 but under a lens the very different apex and sculpture will always dis- 

 tinguish it. It was probably this variety which first led Jeffreys to 

 unite the two species. It will be noticed that the var. zetlandica is a 

 deep-water variety. A very minute form comes from Guernsey, Scilly, 

 Torbay, and the Tripoli coast. 



O. obliqua Aid. — Fine sand, 12 — 20 fathoms. Scilly 40 f. (Burkill 

 and J. T. M.); Birterbuy Bay (Dodd) ! Sutherlandshire, from fish 

 stomachs (Baillie) ! St. Aubin's Bay, Jersey ; Tenby ; Isle of Man ; 

 Connemara ; Killala Bay ; Durness Point, Sutherlandshire. 



This species is always dredged, and rare, but less so at Guernsey 

 than elsewhere. It resembles in miniature Jeffreys' figure of Limncea 

 palustris (which latter is different from Sowerby's), though the sculp- 

 ture of his figure is too coarse ; he makes the spiral striae as prominent 

 as in the next species (O. dolioliformis), but it is not half so distinct, 

 and requires a lens to observe it. Alder's original figure in the 

 "Annals" 1 is perfect in profile, but exhibits no sculpture, although he 

 says " though apparently smooth, specimens when examined with a 

 high magnifier exhibit very minute spiral striae." Fuller particulars 

 of this and the last species will be found in J. Conch., vol. 7, pp. 

 253-4, 1893. Jeffreys' descriptions of both are mixed and unreliable. 



O. dolioliformis Jeffr. — In sea-weeds of rock-pools at low water. 

 Scilly Islands (Burkill and J. T. M.) ; Babbacombe Bay (Cox) ! 

 Jersey, Guernsey, and Herm ; St. Ives and Falmouth ; Torbay ; 

 Margate ; Sutton-on-Sea and Skegness ; Southport ; Durness Point, 

 Sutherlandshire. 



This is the most distinctive shell in the genus, and unlike any 

 other. Nor is it at all variable, except in a slight lengthening or 

 shortening of the spire. It is local and scarce, but not uncommon in 

 some parts of South Devon. It is sculptured spirally with narrow 

 incised lines. Occasionally the periphery is compressed, and this in- 

 flects the middle of the outer lip, thus giving the mouth a different 

 outline. My largest, from Guernsey and Lincolnshire, are a line in 



1 Ann Mag-. Nat. Hist., vol. 13, p. 327, pi. 8, fig. 12, 1844. 



