UNIVALVES PATKLLA. 127 



Those species whicli are more coniprcsed, and liave 

 their margins angularly or irregularly toothed, form the 

 second division: as the P. laciniosa, P saccharina, P. gra- 

 nulatus, P. granatina, &c. The P. vulgata, or common 

 limpet, is found in great abundance on the British 

 shores. 



The P. Magellanica and P. argentea have a metallic 

 gloss diffused over their surfaces, and are therefore calU 

 cd bronze limpets. 



The P. Sinica is one of the rarities of the genus; it 

 sometimes grows to a large size; it is a flat, broad, ex- 

 panding shell, of a blueish white color, having its interi- 

 or of a glossy yellowish or brownish cast, and the tip 

 generally of a beautiful orange color; the margin is often 

 circularly scalloped. This species is generally known as 

 the P. umbellata. 



The next division comprehends the species which 

 are cap- shaped, and have a recurved tip. Of these the 

 P. Hungarica is the most remarkable; it is a beautiful 

 shell, and from its similiarity of shape is called the fool's 

 cap. The exterior is usually of a pale fawn color, and 

 the outer margin is bordered with a fine bristly epider- 

 mis; when the interior is of a very bright pink color, this 

 limpet is considered more valuable. 



The P. lutea has some resemblance to an Haliotis, but 

 the flatness and ear-shaped form of the latter genus is a 

 sufficient distinction. The P. pectunculus is covered with 

 spines, and the P. perversa is remarkable for having its 

 crown recurved, and turned towards the hind part of the 

 animal. 



Of the limpets which are very entire, and not pointed 

 at the the tip or crown, those most worthy of notice are 

 the P. afra, P, Lusitanica, P. areolata, P. flammea, P. In- 



