THE PINNA AND ITS GUARDIAN. Ill 



also between the animals of the two genera. 

 His Xsirag is another shell-fish recognised with 

 facility in the common limpet of the Mediter- 

 ranean ; and his Sea-ear in the Haliotis. Al- 

 though living continually attached to the rock, 

 the ancients distinguished carefully between it 

 and the Balanus, which was fixed to the rock. 



The lepas, we are told by Aristotle, moves 

 and creeps, as do the animals of all turbinated 

 shells. The " History of Animals " is full of 

 such generalizations, most of which are un- 

 shaken. None but a naturalist can appreciate 

 the immense amount of minute observations 

 which must have been made ere they could 

 have been enunciated, and the wonderful 

 sagacity which thus, at the very beginning of 

 a science, perceived those general truths which 

 were to hold good even to its completion. 



Among the bivalve testacea mentioned by 

 Aristotle, we find, on the shores of Asia Minor, 

 the Pinna, living, as he described it, fixed by 

 one extremity, and standing upright in sand 

 or mud, mooring itself by a byssus. Open a 

 few, and in five out of ten you find the little 

 crab, the mvvoTrjpocg, the fabled guardian and 

 cherished friend of the pinna. It is pleasant 



