CLASSIFICATION OF THE BRACHIOPODA. 71 



surface smooth ; structure punctated. Valves articulating by the means of teeth and 

 sockets. In the interior of the smaller or dorsal valve the socket ridges are largely developed, 

 extending to nearly a third of the length of the valve, and fitting into corresponding 

 grooves in the dental valve ; the hinge plate or platform is large and massive, filling up the 

 space between the socket ridges ; and from the extremity of the umbonal beak originates 

 the cardinal process or boss, which assumes the shape of two deviating elongated crests, 

 grooved along their upper surface, and probably serving as an attachment to the cardinal 

 muscles ; pedicle scars are visible on the outer sides of these ; Fig. 17. 

 at the base of the platform above described a short mesial sep- 

 tum gradually arises, to the upper edge of which is affixed an 

 anchor-like pair of lamellae, and close to the base of the septum 

 was attached the adductor muscle. In the dental valve a mesial 

 ridge separates the large cardinal muscular scars placed on either 

 side, and towards the centre of the valve a small ovate im- Bouchardia tuUpa. 



pression indicates the place of the adductor. The ventral ''■ '1:S;^^::tS-ii'^ 

 pedicle-muscles occupy a deep groove, which extends from the ^^"'^' «>««?<»"«■ 



, • n ^ p 1 • 1 • ^^' Ji^t^^'ior of ventral valve; f, 



last-named scar to the extremity 01 the loramen, which is exca- foramen ; t, teeth ; &,adduc- 



.,..,,. i> ii 1 1 tor ; -p, pedicle; r, cardinal 



vated in the substance 01 the beak. muscular scars. 



Obs. The remarkable organisation of this little genus is so different from that 

 observable in the rest of the Terebratulida that I could not refrain applying to it a separate 

 denomination ; unfortunately the animal has not yet been examined, so that little can be 

 said of the soft parts or arms, but the cardinal process presents a very unusual shape and 

 character, and the whole internal details have their peculiarities. 



Geol. range. — 'Hitherto only known in the recent state. 



Example: Bouchardia tulipa, Blainv., sp.= (rosea, Mawe, sp.) 



Genus — Morrisia, Dav., 1852.^ 



Type—M.. anomioides, Scacchi, sp. (=T. depbessa, Forbes.) Int., PI. VI, figs. 30, 31. 



Orthis, Scacchi and Philippi.^ 

 Terebkatula, Forbes.^ 



Shell minute, circular, depressed ; foramen large, round, encroaching equally on both 

 valves ; larger or dental valve with a small straight hinge area : deltidium plates minute, 

 widely separated ; valves articulating by the means of teeth and sockets ; smaller or socket 

 valve deeply notched at the umbo ; apophysary system consisting of two branches, origi- 

 nating at the base of the dental sockets, and united to a small elevated process arising 

 from the centre of the valve. 



1 Annals and Mag. of Nat. Hist., vol. ix, 2d series, p. 361, 1852 ; Proc. of the Zool. Soc, 1852. 



2 Enumeratior Moluscorum Sicilie, vol. ii, pi. xviii, fig. 9, 1844. 

 » Report of the MoUusca of the ^Egean Sea, 1843. 



