260 PATELLIDA. 
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 Laminarie, and when adult, imbedded in the centre of 
their roots. 
P. vuteata, Linneeus. 
P. vulgata, Auctorum. 
, Brit. Moll. ii. p.421, pl. 61. £. 5, 6. 
Animal at the base subcireular, inhabiting a shell of various 
subconical altitudes ; vertex anterior, from which fine strize 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-poited filaments of three lengths, which 
vibrate beyond the shell. The branchiz, 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, havmg 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; tentacula of the different hues of smoke- 
colour, long, strong, conical, sharp-pomted, tumid at the 
base; eyes minute, very little raised at the external bases. 
Foot oval, ight lead-colour above and below, with numerous 
still paler anastomosing lnes; 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 modderate- 
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. levis or P. athletica, as 
they always have access to the Algze, 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 
