PECTEN. 283 



slightly convex. The anterior auricle is decidedly large, 

 but very manifestly shorter in the upper valve ; its angle 

 is a right angle, and its sinus rather large, profound, finely 

 pectinated, and angular below. The interior of the shell 

 displays no peculiarity in hinge or painting; the latter, 

 from the thinness of the shell, being that of the exterior ; 

 the margin is quite entire. 



Onr largest specimen measured ten lines in width, and 

 was slightly inferior (not quite a line) in length ; the 

 middle-aged examples are the more orbicular. 



The animal has a white-margined mantle, marked with 

 distant perpendicular stripes of Sienna-yellow ; on the 

 fixed edges of the mantle-mai'gins are the white cirrhi, 

 and among their bases conspicuous blue-black ocelli, which, 

 when very highly magnified, are seen to have crimson 

 centres ; the shorter cirrhi at the free edge of the mantle 

 are white. The branchiae are yellowish-white, and the 

 body is of a bright orange-yellow. 



This pretty shell, first described as British by Mr. Smith 

 of Jordan Hill, and named by him after our esteemed 

 friend, the Rev. David Landsborough, appears to have 

 been formerly confounded on our shores with ticjrinus. It 

 is a species of boreal origin, and consequently most com- 

 mon on the Scottish shores, and near the outliers of the 

 glacial sea. On the English coast it is very rare, but has 

 been taken off Scarborough (Bean) ; in thirty fathoms, 

 thirty-five miles off Northumberland (King) ; in fifty 

 fathoms, on the same coast (Howse) ; at Whitburn 

 (Abbes) ; and Newton (Embleton). On the west coast 

 of Scotland it is frequent in the Clyde district and the 

 Hebrides ; it occurs also among the Zetlands and Orkneys. 

 The following Scottish localities will show its range: — 

 Orkney, twelve fathoms ; Oban and Skyc, in twenty 



