432 MOLLUSCA. 



CLASS T. 



BRACHIOPODA(l). 



The Mollusca Brachiopoda, like the Acephala, have a bi- 

 lobed mantle which is always open. Instead of feet they are 

 provided with two fleshy arms, furnished with numerous fila- 

 ments, which they can protrude from, and draw into the shell. 

 .The mouth is between the base of the arms. Neither their 

 organs of generation, nor their nervous system are well known. 



All the Brachiopoda are invested with bivalve shells^ fixed 

 and immovable. But three genera are known. 



LiNGULA, Brug. 



Two equal, flat, oblong valves, the summits of which are at the 

 extremity of one of the narrow sides, gaping at the other end, and 

 attached between the two summits to a fleshy pedicle, which sus- 

 pends them to the rocks; the arms become spirally convoluted pre- 

 viously to entering the shell. It appears that the branchiie consist 

 of small leaflets, disposed around the internal face of each lobe of 

 the mantle. 



But a single species Lingula anafina, Cuv., Ann. du Mus.,. 



I, vi, Seb., Ill, xvi, 4, is known. It inhabits the Indian Ocean, 



and has thin, horny and greenish valves(2). 



(1) M. de Blainville has given to my Brachiopoda the name of Pallioekan- 

 CHIATA, and makes an order of them in his class of the AcEPHALOPkoaA-. 



(2) Linn?eus, who knew but one of the valves, called it Patella unguis. So- 

 lander and Chemnitz, who were aware of its having; two, called it, the one, 3'Iytilus 

 lingua, and the other, Pinna unguis. Brugieres knew its pedicle, and conse- 

 quently made a genus of it by the name of Likguia, Encyc. Method., Vers, pk 

 250. . It Is singular that before us, no one had remarked that it is well figured 

 with its pedicle by Seba, loc. cit. 



