70 INTRODUCTION. 



Obs. The animal of this small genus or sub-genus (examined in two species), differs 

 from Megerlia in the relative small size of the cirrated arms. 



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



Examples : K. rubra, Pallas, sp. ; K. cognata, Chemnitz, sp. ; K.pimm, Lamarck, sp.; 

 K. Lamarckiana, Dav. ; K. Deshagesii, Dav.^ 



Genus — Mag as, Sowerbg, 1818.^ 



Type — Magas pumilus, Sow. Int., PI. VI, figs. 19, 21. 



Terebratula (part), Lamarck, V. Buck, Deshayes, &c. 



Magas, of the generality of Naturalists. 



Orthis (Millepunctata), Be Koninck, sp. (not Orthis, Dalman.) 



Animal unknown ; shell small, inequivalve, more or less regularly oval ; beak truncated 



by a foramen extending to the umbo of the smaller valve; surface smooth or slightly 



striated; shell structure largely punctated; apophysary system in the dorsal or socket valve 



Fig. 15. Fig. 16. composed of an elevated longitudinal septum reaching from one 



valve to the other, and to which are affixed two pair of calcareous 



lamellae; the lower ones are riband-shaped, attached first to 



the hinge-plate, they afterwards proceed by a gentle curve to 



near the anterior portion of the septum, to the sides of which 



Magas pumiia. they are affixed; the second pair originate on either side of 



15. Interior of Dorsal Valve, the Upper cdgc of the scptum, extending in the form of two 



echon of at a ves. triangular anchor-shaped lamellae. 



Obs. Having fully described this genus in Part II, p. 19, it will not be necessary to 



add any other observations. 



Geol. range. — Hitherto only known in the cretaceous period. 

 Examples : Magas pumiia, Sow. ; M. orthiformis, D' Archiac, sp. 



Genus — Bouchardia, Davidson, 1849.® 

 Type — B. tulipa, Blainv. sp.=(ROSEA, Mawe, sp.) Int., PI. VI, figs. 22, 25. 

 Terebratula (part), of Authors. 



Shell of an elongated oval shape ; valves thick and almost equally convex ; beak nearly 

 straight and truncated by a small circular foramen ; no true area or deltidium ; external 



^ The last two species are described by myself, in the 'Zool. Proc.,' for 1852. 



2 Min. Con., vol. ii, p. 40, tab. 119, figs. 1 — 5. 1818. — See likewise Bouchard and Davidson 'Bull, 

 de la Soc. G^ol. de France,' vol. v, 2d ser., p. 139, 1848. 



3 Bulletin de la Soc. G^ol. de France, vol. vii, 2d ser., p. 62, pi. i, 1849. * Die. Sc. Nat. 



