74 KELLIAD.E. 



identical) is elongated, with its margins straightish, its 

 hinder extremity a little subangulated above, and its front 

 one subangulated below. The other variety is less pro- 

 duced, its margins more arcuated, and rounded at both ex- 

 tremities. Intermediate specimens possessing the angula- 

 tion of the former variety, with the abbreviated shape and 

 arcuated basal margin of the latter, or the general features 

 of the latter variety with the elongated shape and anterior 

 subangulation of the former one, unite inseparably these 

 two forms. 



The largest example we have seen measures three-eighths 

 of an inch in length ; the majority of specimens do not ex- 

 ceed five-sixteenths of an inch from side to side. 



" The animal of this species," Mr. Alder writes to inform 

 us, " agrees with the other 3Iontacuta, in having the foot 

 exserted at the larger end of the shell, and presenting no 

 apparent tubes. There appears to be only one posterior 

 aperture.'" 



This is a scarce shell, though widely distributed. The 

 larger variety is in most instances sublittoral in its habits, 

 the other ranging to deep water ; South Devon (Jeffreys) ; 

 Dartmouth in seven fathoms (M 'Andrew and E. F.) ; 

 Tenby (S. H.) ; Scarborough (Bean) ; Cullercoats (Alder); 

 Lamlash Bay in Arran (Alder) ; Inverary (Bailee) ; He- 

 brides, Zetland, and Murray Firth (M 'Andrew); St. An- 

 drews (Knapp) ; Frith of Forth (E. F.) ; Belton Sands 

 near Dunbar (Laskey). Cork Harbour (Humphreys) ; 

 Youghal (Jeffreys) ; Birterbuy (Barlee) ; " Dublin coast, 

 whence only I have yet seen specimens 1 "' (W. Thompson). 

 Cape Clear in thirty fathoms (M'Andrew). 



No foreign author notices this species as an inhabitant of 

 other seas than ours. 



