ACEPHALA TESTACEA. 109 



narrow and elongated on the opposite side, and leaving a large ob- 

 lique opening at each extremity ; their hinge, like that of a true Mya, 

 is furnished with a plate projecting from one valve into the other, 

 and with an internal ligament running from that plate into a cor- 

 responding cavity. Their mantle is reflected externally upon the 

 hinge, where it sometimes contains two or three supernumerary 

 calcareous bodies. The foot issues through the aperture on the side 

 next to the mouth, where it is widest, and from the opposite one 

 project the two tubes, which are vinited and susceptible of inflation 

 in every direction. 



The Pholades inhabit canals which they excavate, some in ooze 

 and others in stone, like the Lithodomi, Petricolse, &c. They are 

 much sought for on account of their agreeable flavour. 



Several species are found on the coast of France : such is the 

 Dail commun ; Phola^ dactylus, L. ; Chemn., VIII, ci, 859 *. 



Tekedo, Liv. 



The mantle extended in a tube much longer than the two small, 

 rhomboidal valves, and terminated by two short tubes, the base of 

 which is furnished on each side with a stony and moveable kind of 

 operculum or palette. These Acephala, while quite yoimg, pene- 

 trate and establish their habitations in submerged pieces of wood, 

 such as piles, ships' bottoms, &c., perforating and destroying them in 

 every direction. It is thought, that in order to penetrate as fast as 

 it increases in size, the Pholas excavates the wood by means of its 

 valves; but the tubes remain n3ar the opening by which its entrance 

 was effected, and through which, by the aid of its palette, it receives 

 water and aliment. The gallery it inhabits is lined with a calcareous 

 crust which exudes from its body, and which forms a second kind of 

 tubular shell for it. It is a noxious and destructive animal in the 

 sea ports of Europe. 



Teredo navalis L. This species, which is the most common, 

 and is said to have been introduced into Europe from the torrid 

 zone, has more than once threatened Holland with ruin by the 

 destruction of its dikes. It is upwaads of six inches in length, 

 and has simple palettes. 



Larger species inhabit hot countries, whose palettes are articu- 

 lated and ciliate. They should be remarked for their analogy to the 

 Cirrhopoda. Such is the Teredo palmulatus, Lam., Adans., Ac. des 

 Sc, 1759, pi. 9, f. 12. 



FisTULAXA, Brvg. 



Separated from Teredo ; the external tube is entirely closed at its 

 larger end, and is more or less like a bottle or club. The Fistulanae 

 are sometimes found buried in submerged fragments of wood, or in 



* Add, PhoJas orient alls, lb., 860, which is, perhaps, a mere variety of ductylus; — 

 Phol. cosfata, lb., 863 ; — Phol. crispafa, Id., cii..^872, 874 ; — Phol. pusiUa, lb., 867, 

 871 ; — Phol. striata, lb., 864, 866. 



