116 MOLLUSCA. 



Otliers project in a conical or globular mass*, 



Or expand into a disk comparable to that of a flower or of an 

 Actinia f, or are elongated into cylindrical branches supported by 

 slender pedicles, &c. \ or, form parallel cylinders §. 



Recent observations even seem to show that the Eschars, hitherto 

 placed among the Polypi, belong to this family of the Mollusca|| . 



CLASS V. 



BRACHIOPODA^. 



The Mollusca Brachiopoda, like the Acephala, have a bilobed 

 mantle which is always open. Instead of feet they are provided with 

 two fleshy arms furnished with numerous filaments, which they can 

 protrude from, and draw into the shell. The mouth is betAvecn the 

 base of the arms. Neither their organs of generation, nor their ner- 

 vous system are well known. 



All the Brachiopoda are invested with bibalve shells, fixed and 

 immoveable. But three genera are known. 



LiNGULA, Brug. 



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

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

 attached between the two summits to a fleshy pedicle, which suspends 

 them to the rocks ; the arms become spirally convoluted previously 

 to entering the shell. It appears that the branchiae consist of small 

 leaflets, disposed around the intei'nal face of each lobe of the mantle. 



But a single species — Lingula anatina, Cuv., Ann. du Mus., 

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

 and has thin, horny and greenish valves**. 



* The Euccelium, Savig. ; the Distomi are arranged in the same manner. 



•f- The genws Diazona, Sav., consisting of a large and beautiful purple species 

 discovered near Iviceby M. Delaroche. 



X The genus Sigillina, Sav., whose cylindrical branches are frequently a foot long, 

 and the animals, slender as threads, but three or four inches. 



§ The genus Synocium, Lam. 



II Messrs. Audouin and Milne Edwards on the one hand, and M. de Blainville on 

 the other, have lately verified this fact, which the observations of Spallanzani pre- 

 viously seemed to announce. 



^ M. de Blainville has given to my Br-A-chiopoda, the name of Palliobran- 

 CHiATA, and makes an order of them in his class of the Acephalopuora. 



** Linnseus, who knew but one of the valves, called it Patella unguis. Solander 

 and Chemnitz, who were aware of its having two, called it, one, the Mytilus lingua, 

 and the other, Pinna unguis. Brugi^res knew its pedicle, and consequently made 

 a genus of it by the name of Lingula, Encyc. Method., Vers, pi. 250. It is 

 singular that before us, no one had remarked that it is well figured with its 

 pedicle by Seba, loc. cit. 



