BIVALVIA. 09 



The figure showing the hinge has been copied from a specimen in the British 

 Museum collection. 



LUCINA DESPECTA, Phil. Tab. VI, figs. 16, 17. 



LUCINA DESPECTA, Phil. Geol. Yorksh., i, t. 9, f. 8, 1835. 



CARDIOIDES, D'Archiac. Mem. Soc. Geol. France, torn, v, t. 25, f. 6. 

 DESPECTA, junior, tab. nost. vi, f. 16. 



Testa suborbiculari, obliqud, convexd ; umbonibus parvis acutis, postmedianis, later e 

 antico producto, postico brevi ; superftcie lineis concentricis crebris irregularibus. 



Shell suborbicular, oblique, convex, anterior side produced, posterior side short ; 

 umbones small, acute, situated posterior to the middle of the valves, and curved forwards ; 

 the surface with closely arranged, irregular concentric lines. 



Having had the advantage (through the kindness of Mr. Bean) of comparing the original 

 specimen (fig 17) figured in the 'Geology of Yorkshire,' we are enabled to affirm that 

 Lucina cardioides, D'Archiac (Mem. Soc. Geol. Fran., vol. v, tab. xxv, fig. 6), represents the 

 young of this species (Tab.VI, fig. 16); in that condition the shell is somewhat more convex, 

 the concentric lines are prominent and less irregular than in the adult condition. Lucina 

 obliqua, Goldfuss, (Petref., tab. 146, fig. 14,) is probably another synonym of the same 

 species ; these synonyms having been occasioned by the figure in the ' Geology of York- 

 shire,' unaccompanied by any description not having been fully recognized. 



The numerous specimens which we have examined present a considerable diversity in 

 figure, depending chiefly upon the varying amount of obliquity ; the substance of the test 

 is thick, and in the ultimate stage of growth the concentric plications become both pro- 

 minent and closely arranged. In the shelly beds of the great Oolite the greater number 

 of specimens are diminutive ; in the upper portion of the Inferior Oolite they are much 

 larger. 



Localities. Minchinhampton Common in the Great Oolite; Ponton, Lincolnshire; 

 near Nailsworth, in the Inferior Oolite. 



CORBIS, Cuvier, 1817. 



IDOTJEA, Schumacher, 1817. 



Gen. Char. Shell transverse equivalve, umbones submesial, incurved, contiguous ; 

 surface ynbricated or cancellated. Hinge, with two narrow triangular teeth, in each valve 

 of which one is bifid, and two lateral teeth, the anterior of which are approximate, the 

 posterior teeth remote. Muscular impressions lunulate, pallial impression simple. 



CORBIS LAJOYEI, D' Archiac. Tab. VII, fig. 12, I2a, b. 



COEBIS LAJOYEI, D'Archiac. Mem. Soc. Geol. Fr., torn, v, t. 27, f. 1, 1843. 

 Testa crassd, convexd, transverse elonyatd, umbonibus maynis medianis ; antice sub- 



