PATELLA 



The muscular impression, which is generally very distinct 

 is of the same form as the shell, and placed within, about 

 half way from the summit to the margin ; it is interrupted 

 in front, where the head of the animal is placed; becoming 

 very much narrower, and forming only a transverse line. 

 The outside is sometimes smooth and the margin entire ; 

 but more commonly ribbed or striated in a very variable 

 manner from the apex to the margin, and then the 

 margin is variously crenulated or dentated. There is no 

 canal for the passage of water to the hrancMcBy as there 

 is in Emarginula and Sipho7iaria, for in this Genus the 

 branchiae are external, surrounding the animal. 



Though these animals are endued with locomotive 

 powers, yet they habitually remain for a long time affixed 

 to the same spot : they are very common in all rocky 

 places on the sea coast, frequently forming a hollow place 

 in the rock where they are attached, and being modified 

 in form according to the smoothness or inequalities of 

 the rock: some species are attached to sea- weeds; all, 

 we believe, feed on them. A great number of recent 

 species are known, but we apprehend several, which ought 

 to be considered as mere varieties, are published as dis- 

 tinct species by Lamarck and other authors : it is remark- 

 able that they are wholly omitted in the Encyclopedie 

 methodique. Contrary to the opinion of some celebrated 

 conchologists, we consider the P. Cochlear to be a true 

 Patella. The English name of Limpet is commonly ap- 

 plied to the species of this Genus, of which several are 

 common on our coasts. The more common name given 

 to them in France is Lepas, the original name by which 

 the earliest Greek writers on Natural History designated 

 the Patellae : it is their BacXavos, which corresponds with 

 ^ the Lepas of modern Conchology. 



The fossil species are not numerous; they occur in 

 the great Oolite, Lias, and perhaps in the Oxford clay 

 and Chalk marl of the secondary series; in the Calcaire 

 grossier, and probably in the London clay of the tertiary 

 series; and also in the Crag of the Diluvian formation. 



Fig. 1. Patella melano gramma? 



2. ~ miniata var. in colour. 



3. ■ miniata and compressa in one specimen. 



4. — ferruginea jun. 



5. intorta. 



^. fragilisy Chem. 



