LECTURE XL IBS 



The Multivalves are distributed by Linnaeus into 

 three genera, one of which, named P kolas, has the 

 general appearance of a bivalve; but on close in- 

 spection, will be found to differ; having small or 

 accessorial valves or pieces at the back part of the 

 shell. The inhabiting animal resembles an Asci- 

 dia. The most common species of Pholas is the 

 P holas Dactylus of Linnaeus, a native of the Euro- 

 pean seas : this species has the faculty of piercing 

 and imbedding itself in calcarious rocks, in which 

 it is generally found : the animal is considered as 

 an edible shell-fish, and in some places is regarded 

 as a delicacy. 



The next genus is of a very singular appear- 

 ance, and is called Chiton. It is of an oval shape, 

 and is composed of several transverse pieces; those 

 at each extremity having a rounded outline. The 

 inhabiting animal is shaped like a Doris or Sea- 

 SnaiL The species of Chiton are pretty numer- 

 ous, and there is a considerable degree of general 

 similarity between them. One of the largest is the 

 Chiton squamosus, measuring about three inches in 

 length, and of a greenish white colour. It is a 

 native of the American seas ; but several of this 

 genus are found also about the European coasts, 



