2 CRETACEOUS LAMELLIBRANCHIA. 



1876. LIMA CANALIFEBA, D. Braiins. Zeitschr. f . d. gesammt. Naturwiss., vol. xlvi, 



p. 386. 



1877. A. Fritsch. Stud, im Grebiete der bohin. Kreideformat. : 



II, Weisseuberg. u. Malnitz. Schiclit., 

 p. 132, fig. 117. 

 1893. cf. CANALIFEBA, R. Michael. Zeitschr. der deutsch. geol. Gesellsch., 



vol. xlv, p. 242. 



1898. CANALIFEBA, G. Miiller. Mollusk. Untersenon. v. Braunschweig u. 



Ilsede (Abhandl. 4. k. preussisch. geol. 

 Landesanst. N.F., Heft 25), p. 28. 



1901. H, Imkeller. Kreidebild. am Stallauer Eck (Palaeon- 



tographica, vol. xlviii), p. 32, pi. iii, fig. 10. 

 F. Sturm. Jahrb. d. k. preussisch. geol. Landesanst. 

 fur 1900, vol. xxi, p. 90. 



Description. Shell moderately convex, oval or subtriangular ; height a little 

 greater than length ; outline rounded, except the antero-dorsal margin, which is 

 nearly straight and rather long. Apical angle from 105 to 110. Umbones 

 rather small, close together. Anterior area slightly depressed, with small radial 

 ribs. Anterior ears small ; posterior larger, with growth-lines and faint radial 

 ribs. 



Oz'namentation consists usually of 18, but sometimes of as few as 14 or as many 

 as 21 very strong, rounded, straight ribs, which are separated by broader furrows. 

 In well-preserved specimens numerous concentric linear ridges occur on both ribs 

 and furrows, and projecting growth-ridges are seen at regular intervals on the 

 ribs. 



Measurements : 



(1) (2) (3) (4) (5) 



Length . 70 . 56 . 52 . 43 . 32 mm. 

 Height 1 . 76 . 58 . 54 . 44 . 35 

 (1 5) Upper Greensand, Ventnor. 



Affinities. An exact comparison of the English specimens with the foreign 

 examples of Lima canalifera is rendered difficult owing to the fact that the former 

 have the shell well preserved whilst the latter occur chiefly as casts. In both 

 cases the number and breadth of the ribs show considerable variation. The fine 

 concentric ornamentation is the same in both, as is shown by Goldfuss' figure, but 

 in some of the best preserved English specimens there occur also transverse 

 ridges on the ribs at regular intervals. Somewhat similar ridges are shown in 

 Goldfuss' figure, but they seem to be present chiefly on the sides of the ribs and 



1 In all species of Lima (unless otherwise stated) this is measured obliquely to the hinge-line so 

 as to give the greatest height. 



