UNIVALVES. — PATELLA. 139 



of a beautiful orange colour ; the margin is often circular- 

 ly scalloped. 



Those species which are more compressed, and have 

 their margins angularly or irregularly toothed, form the se- 

 cond division : as the P. laciniosa, P. saccharina, P. granu- 

 lans, P. granatina, &c. The P. vulgata, or common limpet, 

 is found in great abundance on the British shores. 



The third division of the Patella includes the perforated 

 species ; the principal are the P. Grasca, P. nimbosa, P. 

 Caffra, P. perforata, and P. macroschisma; the latter, when 

 in fine preservation, is considered a rarity ; it grows to a 

 considerable size, and is found at Japan. 



The next division comprehends the species which are 

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

 Ungarica is the most remarkable ; it is a beautiful shell, 

 and from its similarity of shape is called the Fool's Cap. 

 The exterior is usually of a pale fawn colour, and the outer 

 margin is bordered with a fine bristly epidermis; when 

 the interior is of a very bright pink colour, 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. pectinata is covered with 

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

 crown recurved, and turned towards the hind part of the 

 animal. 



The species of the sixth division are entire, and furnisli- 

 ed with an internal lip, which is strikingly observable in the 

 P. equestris and P. Sinensis ; some of them are rough and 

 scaly, whilst others are perfectly smooth and polished ; they 

 are known by the name of Cup-and- saucer Limpets. 



The species of the seventh division are chambered or 

 vaulted, and have the appearance of a slipper j such are 

 the P. porcellana, P. fornicata, and P. aculeata. 



