20 CRETACEOUS LAMELLIBRANCHIA. 



Non 1847. — — A. iT Orhiyny. Pal. Franc. TeiT. Cret., vol. iii, p. .'JC4, pi. 



ccccxxiv, figs. 10 — 13. 

 1847. — Mantelli, (VOrhigny. Ibid., p. 568, pi. ccccxxvi, figs. 3 — 5. 



— 18-50. — HoPEEi, d'Orhujny. Prodr. de Pal., vol. ii, p. 248. 



— — — Mantelli, cTOrhigny. Ibid., p. 248. 



1877. — HopERi, A. FritscJi. Stud, im Gebiete der bijhm. Kreideformat. : 



II, Weisseuberg. u. Malnitz. Schielit., p. 134, 

 fig. 121. 



— — — Mantelli, Fritsch. Ibid., p. 134, fig. 122. 



— 1872. — HoPEEi, H. B. Gcinitz. Das Elbthalg<>l>. in SacLsen (Palaonto- 



graphica, vol. xx, pt. 2), p. 40, pi. ix, 

 figs. 11, 12. 



— 1881. — — J- Kiesow. Cenomanversteiu. a. d. Diluvium d. Umgeg. 



Danzig's (Schrift d. naturf. Gesellseb. in 

 Danzig, N. P., vol. v), p. 414, figs. 9, 10. 

 ? — 1893. — sp., cf. HopERi, B. Michael Zeitschr. d. deutscb. geol. Gesellsch., 



vol. xlv, p. 234. 



Descrijitiou. — Shell convex, oval, rounded, considerably inequilateral, longer 

 tlian high. Antero-dorsal margin rather long, slightly convex or nearly straight ; 

 postero-dorsal margin rather short ; the remainder forming a regular curve. 

 Umbones close together. Apical angle 115° to 117°. Ears rather small, with 

 growth-lines; the posterior longer than high and larger than the anterior ear. 

 Anterior area large, deep, with a more or less sharp border, often with radial 

 grooves which vary in number and are more distinct near the umbo than 

 anteriorly. 



Surface of shell nearly smooth. In the region of the umbo numerous linear 

 grooves with pits occur ; these may also extend on to the anterior and posterior 

 parts of the shell, and in some cases they are present on the middle of shell, 

 reaching a part of the way or even quite to the ventral margin. The grooves are 

 slightly wavy, sometimes discontinuous, and are deeper near the anterior and 

 posterior margins, and often more widely separated near the former. 'New 

 grooves are introduced at various distances from the umbo. 



Measurements : 



(1) (2) (3) (4) (5) (6) 



Length 57 57 56 52 51 51 

 Height 52 50 52 50 47 40 



(1) M. cor-anguimini zone, Graveseiid. 



(2) Uintacrinus band, Devizes Road, 



Salisbury. 

 (3, 6, 12) A. quadratus zone. East Harnbam. 

 (4, 7) M. cor-anguinum zone, Gravesend. 



(.5, 10) M. cor-anguinum zone, Northflcet. 

 (8) Chalk Rock, Underwood Hull, Dulliii 

 bam. 

 (9, 11) B. mucronata zone, Norwich. 



Affinities. — This species was described by Brongniart under the name ri(i<jios- 

 tnnia Miiiif'-lli from spccimeTis wliich wore sent to him by Mantcll from near 



