260 PATELLID7E. 



The remarks on this species are inconveniently extended, in 

 consequence of conchologists insisting on two of its forms 

 being distinct. 



These animals are found, when young, on the broad leaves 

 of the Laminarice, and when adult, imbedded in the centre of 

 their roots. 



P. VULGATA, Linnaeus. 



P. vulgata, Auctorum. 



, Brit. Moll. ii. p. 421, pi. 61. f. 5, 6. 



Animal at the base subcircular, inhabiting a shell of various 

 subconical altitudes ; vertex anterior, from which fine striae or 

 rough ribs radiate, accompanied by distinct concentric lines of 

 increase. Mantle pale lead or smoke colour, even with the 

 margin of the cone, except that it is edged with pale brown, 

 very fine, sharp-pointed filaments of three lengths, which 

 vibrate beyond the shell. The branchiae, with respect to the 

 mantle, body and head, are placed as in the last species ; they 

 consist of a cordon of pale lead-coloured, strong, close-set, sub- 

 circular plates, having the outward edges slightly margined. 

 Head large, lead-colour ; aperture of the mouth with a trans- 

 verse or vertical fissure, often puckered, dependent on the 

 will of the animal ; teritacula of the different hues of smoke- 

 colour, long, strong, conical, sharp-pointed, tumid at the 

 base; eyes minute, very little raised at the external bases. 

 Foot oval, light lead-colour above and below, with numerous 

 still paler anastomosing lines ; margin thin, with a pale 

 border ; it is fastened to the body by a very powerful long 

 pedicle, the adhesive muscular powers of which defy the efforts 

 of the strongest man to move, without aid, even in moderate- 

 sized examples. The buccal mass of corneous plates, coiled 

 tongue, and other organs, are so nearly identical with those of 

 the preceding species, that we refer to it to prevent a repetition. 



How many of these creatures exist is a mystery; which 

 remark does not apply to either P. lavis or P. athletica, as 

 they always have access to the Algae, and are submerged many 

 hours out of the twenty-four. But the P. vulgata are often 

 fixed for months, perhaps years, on rocks, at altitudes where 

 they can rarely, if at all, be aspersed by the sea, and are 



