MARSHALL: ADDITIONS TO "BRITISH CONCHOLOGY." 287 



Drobak in Christianiafiord, 60-100 f., and several parts of the Mediter- 

 ranean. 



Var. tumida Jeffr. — Scilly 40 f. ; Borough Island and Torbay ; 

 Knapdale Lochs 11 f. ; Oban 25 f. ; Loch Linnhe 27 f. ; Loch Inver 

 25 f. ; Stornoway 9 f. This variety is also sometimes smooth. A 

 form of the type having a shorter spire and a longer body-whorl is 

 found almost everywhere with the type ; but this variety, besides having 

 the same proportions, is broader throughout, and of an oval shape. 

 Sars figures this short-spired form as his "forma typica," while our type 

 form he calls var. nobilis (pi. ii., f. n-12). 



In Sowerby's figure the mouth is nothing like it should be, and the 

 whorls should be turreted; Jeffreys' is better in outline, but the apex 

 should be obtuse, and the spiral sculpture should not be exhibited 

 throughout the shell, but only on the lower part of each whorl ; 

 Forbes and Hanley's has the same faults as Sowerby's. As in the 

 last species, the three principal authors figure three different forms, 

 neither of which fairly represent the shell. 



The spiral sculpture of this species is of every degree, being some- 

 times easily visible to the eye, even inside the aperture, and at other 

 times obscure even with a lens. In some rare cases the spiral lines 

 are limited to one or two only on the periphery, as in O. nivosa. The 

 umbilicus does not become fully developed until the shell is mature, 

 and even then is unusually variable. Generally speaking, it is small 

 though distinct, but specimens occur which are without a trace, 

 while in others it is large and open, and approached by a canal 

 formed by the reflection of the inner lip. It is more plentiful at 

 Guernsey than elsewhere, and the largest come from Jersey ; I have 

 specimens thence a quarter of an inch in length. A small and 

 slender dwarf form, from Loch Inver and the Sound of Sleat, has 

 the outlines of O. diaphatia. Monstrosities are very rare; I have 

 only one distorted specimen, and have seen few others. 



O. oblongllla Marsh. (/. of Mai., vol. 4, p. 38-9, f. 3, 1895)— 

 The Minch 72 f. 



Var. ovata Marsh. {Ibid.) — The Minch 72 f. 



O. diaphana Jeffr. — In fine sandy mud, 10 to 90 fathoms. Scilly 

 Islands 40 f. (Burkill and J. T. M.) ; Loch Inver 25 f. ; Loch Bois- 

 dale 30 f. ; and Sound of Sleat 70-90 f. (Somerville and J. T. M.) ; 

 S. W. Ireland 5-5 2 f. (R.I. A. cruise); Jersey, Guernsey and Sark 12-22 f. ; 

 Falmouth 19 f. ; Cawsand Bay, Plymouth, 12 f. ; Salcombe, from 

 stomach of a flounder ; Borough Island and Torbay ; off Exmouth, 

 Dawlish, and Teignmouth ; Bantry, Connemara, and Killala Bay ; 

 Eigg Island 20 f. ; Iona 16 f. ; Clyde 18 f. ; the Minch 25-72 f. ; off 

 Peterhead 50 f. ; West Orkneys 45 f. ; Pentland Frith 35 f. ; Hascosy 



