MARSHALL: ADDITIONS TO "BRITISH CONCHOI.OGY." 333 



Another remarkable variety comes from Barra in the Outer 

 Hebrides, and also from Brora in Sutherlandshire ; it is thin and 

 oval, the mouth is wide and patulous, but shorter; only the nipple 

 appears above the crown, and the latter is sloping instead of 

 shouldered. This very much resembles in shape and size, but not in 

 sculpture, U. lima Brown, an Arctic and a Clyde glacial species, well 

 figured by Sars, but badly by Brown. This thin oval form is 

 estuarine, and has what may be considered its marine counterpart 

 in a shell which, except in size, exactly resembles U. avenarms 

 Wats., and which, the author says, " a good deal resembles not 

 Bulla hirrita Moll, but Sowerby's figure of that species in the 

 'Thesaurus'"; but I hope to show further on that B. turrita is only 

 a synonym of U. obtusus. However that may be, these specimens, 

 which I dredged between Guernsey and Sark, are narrowly oval in 

 shape, the upper part is sloping, and the apical whorls project from 

 the main one just enough to be visible. Except in being one-half the 

 size, and the tops of the whorls more distinctly keeled, they agree in 

 the most minute particulars with the diagnosis and figures of Wat- 

 son's U. avenarms, from Port Jackson, Sydney, 2-1 of.^ 



Bulla pertenuis Migh., an Arctic and N. American shell, is the same 

 thing as our estuarine form, though somewhat shorter and broader ; 

 while B. turrita Moll., also Arctic and N. American, " closely 

 resembles and corresponds to our var. lajofikaireofia" (Jeffreys), and 

 is our marine form. B. pertenuis is well figured by Sars,^ and shows 

 it to be like a short and stumpy estuarine U. obtusus, which can be 

 easily matched from Skegness, Portland, and several other places on 

 the British coasts. Forbes and Hanley say that " Bulla pertenuis 

 Migh. so closely resembles the var. jeve?-ensis that the difference is 

 scarcely appreciable."'^ But Bulla ieverensis Schr. is a synonym of 

 U, truncatulus, and not of U. obtusus. 



As to Bulla turrita Moll., the only noticeable feature in examining 

 large series of them is that many appear broader and squarer at the 

 top, with a tendency to attenuate towards the bottom, true var. 

 lajonkaireana being cylindrical ; but the former characters accord 

 with many specimens from Jersey, and agrees better with our 

 marine form than with the var. lajonkaireana (with which Jeffreys 

 allies it). The protrusion of the apical whorls, though extremely 

 variable, is rarely so pronounced as in var. lajonkaireana, being 

 usually only just visible, and in some cases just level with the crown 

 or disappearing from view. An examination of full series of the 

 above forms (particularly from Jersey) will demonstrate that Bulla 



1 'Challenger' Gastropoda, p. 658, pi. xlix., fig. 5. 



2 Moll. Reg. Arct. Norv., tab. 17, fig. 19. 



3 Brit. Moll., vol. iv., p. 286. 



