108 



CRETACEOUS LAMELLIBRANCHIA. 



1899. MoDioLA CoTT^., A. Hemi'ig. Bihang till k. Svenska Vet.-Akad. Handl., 



vol. xxiv, p. 13, pi. i, figs. 16 — 19. 



1900. — CuviERi. A. WoJlemann. Die Biv. ti. Gastrop. A. deutsch. u. 



hollilnd. Neoc. (Abhandl. d. k. preuss. geol. Laud., 

 N. F., pt. 31). p. 68. 



Noil 1847. Mytilus lineatu.s, /. Midler. Petref. Aachen. Kreidef., pt. 1, p. 34. 

 — 1889. Septifer lineatus, Fj. Hohopfel. Die Molhisk. Aachen. Kreide (Palison- 



tographica, vol. xxxv), p. 216, pi. xxv, figs. 10 — 13 

 (these figures are enlarged three times). 



Description. — Shell tliin, ovate-oblong, inflated, regularly convex from the umbo 

 to the posterior extremity, more or less compressed at right angles to its greatest 

 length (dorso-ventrally) ; slightly curved or occasionally straight. Dorsal margin 

 slightly convex. Posterior extremity well rounded, a little expanded. Antero- 

 ventral margin slightly concave, sometimes straight. TJmbones small, curved, 

 terminal. Carina faintly marked near the umbo, absent elsewhere. Antero -ventral 

 face of the shell flattened or concave, postero-dorsal part regularly convex. 



Ornamentation consists of fine but well-marked radial ribs, crossed by rather 

 less distinct concentric ribs, giving a cancellate appearance ; the radial ribs are 

 serrate or granular where crossed by the concentric ribs. At intervals fairly strong 

 growth-lines occur. An oval area below the umbones is without radial ribs, and 

 shows only lines of growth. 



Measurements : 























Umbo to posterior 



(1) 



(2) 



(3) 



(4) 



(5) 



(fi) 



(7) 



(8) 



(9) 



(10) 



extremity 



49 



42 



42 



41 



S7 



;34 



82 



29 



36 



28 mm 



Greatest diameter at 























right angles to pre- 























ceding . 



18 



15 



14 



14-5 



14 



12 



12 



12 



15 



n „ 



Thickness 



20 



25 



23 



2G 



22 



20-5 



15 



15-5 



21 



10 „ 



(1 — 3, 6) from the Hythe Bods, Lympue. 



(4) „ Chalk Marl, Chardstock. 



(5) ,, ,, Kempstone Rocks. 



(7) ,, ,, Duuscombe. 



(8) „ „ Titherleigh. 

 (9, 10) „ Chalk Rock, Cuckhamsley. 



Das Elbthalge- 



Affinities. — The specimens figured by Geinitz as M. Gottx in 

 birge in Sachsen ' agree perfectly with our examples from the Cenomanian. The 

 figures of M. Gottae given by earlier authors appear to represent imperfect or 

 crushed specimens, and I follow Geinitz, who was probably acquainted with the 

 originals, in regarding them as the examples of M. Gottae. 



Modiola angusta, Romer, is considered by Wollemann to be identical with M. 

 lineata ; I have seen no examples of it. 



