ANIMALS INHABITING BIVALVES. 15 



the Patella than any other*, and belongs to the natural family 

 of the Umax of Linnaeus. The animal of the Lepas, called a 

 Triton by Linnaeus, if not a species of Polypus, is nearly allied 

 to it ; and the animal of the Plwlas is an Ascidia, one of the 

 families composing the Bivalves. 



OF THE ANIMALS. 



The animals of the Bivalves, together with the Pholas, form 

 a natural division (the Headless MoUusca of Lamarck), which 

 may be subdivided into four families. None of these have any 

 tiling that can be properly called a head, but are furnished 

 with either one or two tubes, by means of which they draw in 

 their food along with the water, wliich is emitted again by the 

 same tube in those that have only one, and by the other tube in 

 those that have two. 



In the animals of the first family called Ascidia -f, the 

 membrane named by M. Adanson manteau (which is attached 

 to each valve) is united in front, forming a kind of bag or 

 tube, apparently open at both ends, from the \ipper end of 

 which two conjoined tubes project, which are often of consi- 

 derable length ; and from the lower end a short obtuse foot. 

 This family includes the genera Pholas, the tnie Mya, and the 

 Solen of Linnaeus, but not the two species of Mya Pictorum and 

 mai'garitifera. 



* See Adanson's Ilistoire NatureUe du Senegal, p. 42. 

 + Ibid. pi. 19. f. Tagal and lulan, p. 256 and 262. 



