BRACH10PODA. 11? 



TKKKBRATULA, Brag. 



Two unequal valves united by a hinge; the summit of one, more 

 salient than the other, is perforated to permit the passage of a fleshy 

 pedicle which attaches the shell to rocks, madrepores, other shells, &c. 

 Internally, a small bony i>i < . t.f frame-work is observed, that is some- 

 times very complex, composed <-f two branches which articulate with 

 the unperforated valve, and that support two arms edged all round 

 with a lung close fringe, between which, on the side next to the large 

 valve, is a third, simply membranous and much longer appendage, 

 usually spirally convoluted, and edged, like the arms, with a fine and 

 close fringe, the mouth is a small vertical fissure between these 

 three large appendages. The principal part of the body, situated 

 near the hinge, contains the numerous muscles which reach from one 

 valve to the other, and between them are the viscera, which occupy 

 but little space. The ovaries appear to be two ramified productions, 

 adhering to the parietes of each valve. I have not yet been able to 

 ascertain exactly the positon of the branchiae. 



Numberless Terebratukc are found fossil or petrified, in certain 

 udary strata of ancient formations*. The living species are less 

 numerous f. 



The shell of some is transversely broader or longer, in a direction 

 perpendicular to the hinge, with an entire or emarginated contour, 

 with two or several lobes; some of them are even triangular; the sur- 

 face is smooth, sulcated in radii, or veined ; they are thick or thin, and 

 even diaphanous. In several of them, in lieu of the hole in the 

 summit of the thin valve, there is a notch, and this notch is sometimes 

 partly formed by two accessory pieces, &c. It is probable that when 

 T known, their animals will present generic differences. Already 

 in the 



SPIRJFKR, Sowerby, 



Two large cones have been recognized, formed of a spiral thread, 

 which appear to have supported the animalj, In 



THECIDEA, Def., 



The pedicle seems to have been incorporated with the small 

 valve . 



M. Defrance distinguishes upwards of two hundred. 



t Anomin scobinata, Gualt., 96, A; An. aurila, Id., Ib., B; An. retusa ; Am. 

 trunrata, C'lu-imi., \ "1 1 1, Ixxsii, 7 1 1 ; An. capensis, Ib., 703; An. pubescent, Id., 

 l\\\iii, 702; An. detruncala, Ib., 705; An. sanyvinolenla, Ib., 706; An. vitrea, 

 lh., 7<>7, 709; An. dorsata, Ib., 71<>. 711 ; An. psittacea, Ib. 713; An cranium, &c. 



For the fov.il tprcies, see Encyc. Method. Vers, pi. 239 246. 



J For this genus see Sowcrb., Min. Conch, and the article Spin/ere of M. De- 

 france, Diet, des Sc. Nat. t. L. 



ThcrM'.i mniitcn;,,,. iiist. Nat. de la Fr. Merid., IV, f, 183; Th. 



! ;j. Mont. St IVrrr, pi. xxvii, f. 8. Further, and more prect.-e ob>< 

 t inns are requisite, to enable us to class the MAGAS of Sowerby, the STRIGOCE- 

 PHALA of Defrance, and some other neighbouring group . 



