120 PYRAMIDELLID.E. 



5. O. Lu'kisi ^, Jefireys. 



0. Lid'isi, Jeffr. in Ann. & Mag. N. H. 3rd ser. iii. p. 112, pi. iii. f. J9 a, b. 



Shell nearly cylindrical, solid, opaque, glossy : sculpture, 

 only very slight and almost microscopical scratch-like longi- 

 tudinal striae : colour ivory-white : spire abruptly terminating : 

 whorls 5-6, convex, compact, gradually enlarging : the penul- 

 timate one projects a little, and is nearly as broad as the last, 

 which occupies about three- fifths of the shell: suture rather 

 deep : morith oval, contracted above and expanded below, some- 

 what exceeding in length one-thii'd of the spire ; throat quite 

 smooth : outer lip incurved on the periphery : iimer lip 

 thickened and spread on the pillar, joining the outer lip at the 

 upper corner of the mouth, and slightly reflected on the lower 

 side : umhilicus small but distinct : tooth small, prominent, and 

 placed opposite the umbilicus : op>erculum yellowish, with a 

 white streak in the line of the spire, very slightly striated 

 across ; flap broad ; there is the same groove and corresponding 

 ridge as in 0. cono'klea. L. 0-1. B. 0-045. 



Habitat : Guernsey^ 18-20 i., clead^ and Lulworth, 

 10-12 f., living (J. G. J.) ; among seaweeds at low- 

 water mark on the south Devon coast^ living (Webster); 

 Cornwall (Hockin) ; Dogger bank (J. G. J.) ; Bun- 

 doran, co. Donegal^ in drift shell-sand (Waller) ; Oban, 

 dredged in 20-25 f. (M'Kenzie) ; Skye and Shetland 

 (Barlee and J. G. J.). 



This shell is remarkable for its ivory whiteness and 

 solidity, in which respects it agrees with 0. cono'idea ; 

 but that species has a more or less distinct peripheral 

 keel, the suture is not so deep, and the throat or inside 

 of the outer lip is invariably grooved, like the barrel of 

 a rifle. Should the latter, however, prove not to be a 

 permanent character, this species may be regarded as a 

 sublittoral variety of 0. cono'idea. The umbilicus is de- 

 veloped in the adult only of the present species. From 



* Named in honour of the late Dr. F. C, Lukis, an excellent naturalist 

 at Guernsey. 



