172 (CRETACEOUS LAMELLTBRANCHTA. 



? 1885. Pecten ELONGAius, J^. Ni'itting. Die Fauna <1. baltisch. Crnoman. (Palae- 



out. Ahliandl., vol. ii), p. 20, jil. iii, 

 fig. (>. 

 1887. — — A.Peron. Hist, du Terr, do Craie (Bull. Sue. Sci. 



hist, et nat. dc rYoime, ser. 3, vol. xii), 

 p. K!3. 

 1893. — — B. Michael. Zeitschr. d. deutsch. geol. Gesellsch , 



vol. xlv, p. 235. 



1895. — (Chlamts) elongatus, E. T!c><f<en. Had., vol. xlvii, p. 468. 



1896. — ELONGATUS, A. J. Jitldf-Browiie and W. Hill. Quart. Journ. 



Geol. Soc., Vol. Iii, 

 p. 151. 

 1900. — — Jul-es-Browne. Cret. Eoclvs of Eritaiu (Mem. Geol. 



Survey), vol. i, p. 451. 



Nou 1833. — —A. Gohlfms. Petref. Germ., vol. ii, p. 59, pi. xciv, 



_ 1844-. — — F. M'Coi/. Garb. Limcst. Foss. Ireland, p. 92, pi. xvi, 



fig. 9. 



— 1846. — coMATiiS, A. E. Rcufis. Die Verstein. der bolim. Ki-eiddforniat., pi. 



2, p. 29, pi. xxxix, fig. 13. 

 ? — - — — OBLiQUUS, Beiiss. Ibid., p. 29, pi. xxxix, fig. 18. 



— 1871. — ELONGATUS, J. Pliillij^s. Geol. Oxford, etc., p. 441, pi. xvii, 



fig. 19. 



Description. — Shell ovate, pointed dorsallj, higher than long, of little convexity, 

 nearly equilateral. Ears rather large, very nnequal. Apical angle from 78° to 

 a])out 90''. 



Right valve flattened or slightly convex, ornamented with numerous ribs, which 

 are frequently grouped in triplets — a larger central rib with a smaller on each 

 side — but sometimes occur in pairs or singly. The smaller ribs appear at varying 

 distances from the umbo in different specimens. Each rib bears many lappet-like 

 scaly projections ])laccd transversely ; those are sometimes close together and 

 arranged very regularly, l)ut may ])e more distant and somewhat irregular. In 

 places fine growth-ridges are present. The grooves between the ribs are rather 

 narrow and rounded. NarroAv portions of the valves at the antero- and postero- 

 dorsal margins are without ribs, but are covered by numerous fine grooves ])laced 

 nearly perpendicularly to the plane of junction of the valves. Ears Avitli radial ribs, 

 which are often indistinct, nnd with well-marked growth-lines ; on the posterior ear 

 stria> (like those on tlie margin of the valve) are sometimes seen crossing the ribs ; 

 anterior ear large with a deep sinus, posterior ear smaller, triangular. 



Tjcft valve of moderate convexity with ornamentation similar to that of the riglit 

 \a]\('. l^];irs ti'iangular, with many spiny ril)s; the anterior larger than the 

 posterior. 



