52 



are pure white on both surfaces. The membranous marginal 

 areas of the mantle are elegantly arranged in meandering 

 lines of pale red, brown and yellow, forming various-shaped 

 lozenges. "When the valves are opened, and the mottled 

 surfaces of the double margins of each valve are in conjunc- 

 tion, and the various circles of filaments and cirrhi fully ex- 

 serted in a shallow basin of sea- water, it is scarcely possible 

 to conceive a more beautiful and interesting appearance. 

 There are two rows of sea-green ocelli relieved at one part of 

 the circle by a black point, with the pearly pupils deeply 

 sunk in their hollows; there is usually a large eye under 

 each rib of the shell ; the others are much smaller, deposited 

 in a row under them; they all amount to about thirty to 

 thirty-five. The branchise are small for so large a species; 

 there are a pair of palpi on each side, pale drab or brown, 

 laterally attached, folding on each other, subquadrangular, 

 composed of twelve to fifteen strands pectinated on both sur- 

 faces, but more intensely on the inner ; the buccal fringes are 

 two rows of very bright red, well-foliated and branched fillets, 

 which connect the palpi ; the mouth is in the centre of them. 

 The body, and the ovariuin amalgamated with it, are of very 

 small volume and usually white. The foot is snow-white, 

 short, grooved, with a spatulate extremity. The liver is quite 

 dorsal, black-brown, or an intense dark green. The brown 

 suboval secreting glands on each side are as conspicuous in 

 Pecten as in Ostrea. 



We may observe, that in all the Pectines the mass of the 

 organs is small, and appears scarcely commensurate with the 

 area of the shell ; perhaps the deficiency is made up by the 

 mantellar extensible margins and cirrhi, which coast the pe- 

 riphery, being only interrupted by the very short ligamental 

 area, from which point, on each side, they gradually increase 

 in width and size to the centre of the aperture. The animal 

 can effect a rapid progression by flapping together the valves, 

 with the ventral margins in front and the flat valve upper- 

 most. 



This elegant and edible species, the Prince of the British 

 Pectines, is frequently taken in the coralline zone at Exmouth. 



