CRENELLA. 105 



Description. — Shell siibqiiadrate or oval, short, inflated — especially anteriorly 

 and between the umbo and the postero-ventral extremity ; on each side of this line 

 the shell is compressed, and on the ventral side it is flattened. Hinge-margin 

 relatively short ; posterior margin curved, oblique ; ventral long, nearly straight. 

 Postero-ventral angle rounded. Umbo prominent, extending beyond the short 

 anterior margin. Ornamentation consists of numerous fine regular radial ribs, 

 crossed by finer concentric ribs, which are best marked on the dorsal part of the 

 valves ; also at intervals a few well-marked growth-lines. 

 Measurements: 



(1) (2) (3) 



Length ... 16 . 1-i . 13 mm. 



Height ... 11 . 9 . 8-5 „ 



Thickness . . . 13-5 . 12-5. 11 „ 



(1—3) all from Atherfield. 



Ajfflntties. — This is distinguished from the other Cretaceous species ^ by its 

 more quadrate outline. It may, perhaps, belong to the sub-genus Bhomboidella, 

 Monterosato. 



Ti/pes. — I have not seen the type ; it came from the Hythe Beds, near Hythe. 



Blstrlhutlon. — Ferua-hQ^ of Atherfield and Redcliff. Crackers of Atherfield. 

 Hythe Beds near Hythe, and near Maidstone. 



Genus — LrrHODOMUS, Cuvter, 1817. 

 (' Le Rcgue Animal,' vol. ii, p. 471.) 



LiTHODOMUS EUGOSUS? (V Orhl(j}iAj, 1845. Plate XVII, figs. 14 o, h. 



1845. LiTHODOMUS EUGOsus, A. d'Orbigny. Pal. Franc. Terr. Crct., vol. iii,p. 294, 



pi. cccxlvi, figs. 1 — 3. 

 1850. _ _ _ Prod, de Pal., vol. ii, p. 166. 



1867_ — — E. Guerarujer. Album Paleont. de la Sartlie, p. 18, 



pi. xxiii, figs. 18—20. 

 1873. — — H. B. Geiiutz. Das Elbthalgeb. in Saclisen (Palseon- 



tographica, vol. xx), pt. 1, p. 219, pi. Ii, figs. 



24—26. 



Description. — Shell elongate, oval, subcylindrical, dorsal and ventral margins 

 nearly parallel, extremities rounded. Surface with strongly marked growth-lines. 

 Umbones not terminal. 



1 0. concentrica, Gabb ; C. elegantida, Meek and Hayden ; C. sericea, Conrad ; C. granulato- 

 cancellata (Komer) ; C. inflata (Miill.). 



14 



