PATELLA. LIMPET. 137 



6. Patella pcllucida. Blue-rayed Limpet. 



Lister, pi. 543, f. 27 Pennant, pi. 93. f. 4, right hand, 

 middle fig. Da Costa, pi. 1 . f. 5 Donovan, pi. 3. f. 1 

 Dorset Cat. pi. 23. f. 5. 



Shell very thin and transparent, oblong-oval, regularly 

 convex, quite smooth, of a pale yellowish-horny color and 

 nearly the same inside : crown obscure, near one end, 

 marked with a dark blue or purple spot, from which ema- 

 nate from three to seven dotted lines of the richest azure 

 blue, but generally four in number, and extending longitu- 

 dinally towards the opposite margin : length hardly three 

 quarters of an inch ; breadth about half as much. 



On the leaves and stalks of Fuci. v. v. 



7. Patella laevis. Smooth Limpet. 

 Lister, pi. 542. f. 26-Da Costa, pi. 1. f. 6, 



Patella pellucida. Pennant, pi. 93. f. 4, left hand mid- 

 dle, and lower fig. Dorset Cat. pi. 23. f. 6\ 



Patella caerulea. Montagu, Suppl. p. 152. 



Shell oval, rather thick and nearly opake, smooth, or 

 faintly ribbed longitudinally and finely striate concentrically, 

 sometimes flattish with the crown near the margin, and 

 sometimes rather conical with the crown more central, 

 often marked with rays of blueish red or brown, which are. 

 sometimes very few in number, but frequently surrounding- 

 the whole shell : color varying from blackish-brown tq 

 reddish or pale horn-color : crown obtuse, with mostly an 

 impressed circular line a little below the tip, giving it the 

 appearance of having a smaller shell placed on the top of 

 the larger; inside opalaceous, reflecting various shades of 

 white blue purple qr red, especially about the margin which 

 is generally thick : diameter about an inch. 



Variety. With a black spot on each side of tfce crown. 



Patella bimaculata, Montagu, pi. 13. f. 8. 



It has often been a matter of surprise to us, that these 

 two last species should have been consolidated into one, 

 as in no single instance have we been able to discover the 

 slightest trace of approximation or transfer from the P. pel- 

 lucida into this last, by age or any accidental circumstance, 

 either in general appearance, color, consistence, formation. 

 ! w 3 ' 9f 



