58 CRETACEOUS LAMELL1BRANCHIA. 



Non 1842. CrcTTLL^E a. glabra, P. Matheron. Catal. method, et descript. des Corps foss. 



du Bouches-du-Rhone, p. 161. 



— 1843. — — H. B. Geinitz. Die Versteiu. von Keislingswalda, 



p. 14, pi. iii, figs. 4 — 7. 

 ? — 184G. Aeca (Ctjcxjll^a) glabra, A. E. Beuss. Die Verstein. der bohm. Kreide- 



format., pt. 2, p. 13, pi. xxxiv, fig. 44 ; pi. 

 xxxv, figs. 1, 2. 



— 1847. — glabra, J. Miiller. Petref. der Aachen. Kriedeformat., pt. 1, p. 18. 



— 1847. CucttlLjEa glabra, Miiller. Ibid., p. 19. 



— 1858. Aeca fibrosa, J. Vilanova y Piera. Mem. geog.-agric. de Castillon, 



pi. ii, fig. 13. 

 ?— 1863. C ucull^: a glabra, B. Drescher. Zeit. d. deutsch. geol. Gesellsch., vol. xv, 



p. 349. 

 ?— 1875. Arca glabra, R. B. Geinitz. Das Elbthalgeb. in Sachsen (Palaeonto- 



graphica, vol. xx), pt. 1, p. 221, pi. xlix, figs. 1, 3. 

 ? — 1881. — fibrosa, J. Kiesow. Schrift. d. nat. Gesellsoh. Danzig, N. F., vol. v, 



p. 410. 

 ? — 1885. Cucull^ia glabra, F. Notling. Die Fauna der baltisch. Cenoman- 



geschiebe (Palseont. Abhandl., vol. ii), p. 25. 

 ? — 1897. ' — (Idonearca) glabra, B. Leonhard. Die Fauna der Kreide- 



format. in Oberschlesien. (Palaeonto- 

 graphica, vol. xliv), pp. 21, 51. 



Description. — Shell subrhomboidal or more or less oval, a little inequilateral 

 and oblique; high, convex. Anterior margin curved, passing gradually into the 

 ventral margin, and joining the hinge-line at a slightly obtuse angle. Posterior 

 margin nearly straight, oblique, forming with the hinge-line an obtuse angle, and 

 with the ventral margin an acute angle more or less rounded. Umbones large, 

 with a rounded but usually well-marked carina extending from each to the 

 postero-veutral angle of the valves. Sometimes a thread-like ridge, crenulated, 

 passes from the umbo of the right valve to the middle of the posterior margin. 

 Hinge-area long, but comparatively narrow; with three or four, sometimes 

 more, ligament-grooves on each side. Ornamentation consists of numerous radial 

 ribSj sometimes raised and somewhat granular, crossed by concentric growth-lines. 

 Hinge-line long, with from five to eight central transverse teeth, and three or four 

 long lateral teeth, placed parallel or nearly parallel to the hinge-line, and striated. 

 Posterior adductor plate large. Anterior adductor impression smaller. Margins 

 of valves entire. 



Measurements : 



Length 

 Height . 

 Thickness 

 Hinge-line 

 Affinities. — The forms described by Sowerby under the names Cucnllxa glabr 



(1) 



74 



(2) 



55 



(3) 



47 



(4) 



37-5 



(5) 



36 



(6) 



22 



(7) 



21 mm. 



61 



51 



41 



35-5 



30-5 



21 



21 



62 



46 



40 



28 



31 



21 



15 „ 



60 



44 



35 



27 



29-5 



17 



16 „ 



