138 EOCENE MOLLUSCA. 



Marginella ebtjunea, Desk. 1830. En. Meth. (Vers), vol. ii, p. 413, No. 13. 



— — Bronn. 1831. Ital. Tertiargeb., p. 18, No. 53. 



— — Desk. 1824-37. Descr. des coq. foss., &c, vol. ii, p. 707, t. 95 



figs. 14—16, and 20— 22. 



— —J. Sow. 1850. Dixon's Geo!., &c, of Suss., p. 107. 



— — 1 Phil. 1851. Palseontographica (Tert. Foss. Magd.), vol. i, p. 79, 



No. 174. 



— — 1 Beyrich. 1853. Die Conchyl. des Norddeutschen tert., vol. i, 



p. 52, t. 2, figs. 9 a, b. 

 Nee. — — Grat. 1838. Cat. Zool., &c, de la Gironde, p. 50, No. 478. 



nee. — — Grat. 1845. Conch, foss., &c., de l'Adour, t. 1, (Tarriere, &c.,) 



figs. 38 -40. 

 nee. — — Sismon. 1847. Syn. meth., &c., Pedemont. Foss., p. 42, No. 46. 



M. testa parvd, ovato-elongatd : spird acuminata, ultimo anfractu breviori ; anfractibm 

 convexiusculis, ad suturam confluentibus ; aperturd angustd ; labro postice sinuato, extus 

 marginato, intus mutico ; columella quadriplicatd. 



Shell small, elongated, with an elevated pointed spire, rather shorter than the 

 aperture, and formed of five or six narrow, slightly convex whorls, somewhat depressed 

 round the sutural margin, the sutures concealed by the enamel ; body- whorl conoidal ; 

 aperture elongated, narrow, obscurely notched in front ; lips nearly parallel ; outer lip 

 with a wide and moderately deep sinus at the suture, thickened and presenting a raised 

 border along the outside margin, smooth within ; columella nearly straight, and fur- 

 nished with four narrow, almost equal folds, the front two of which are more oblique 

 than the others. 



M. Deshayes, when he separated M. hordeola, suggested at the same time that it 

 might be only a variety of the present species ; Dr. Beyrich in fact maintains the 

 identity, and that the only distinction is the difference of size. I do not concur in this 

 opinion. Both species belong to a group, in several of which the characters depend, 

 to a great extent, on the condition of the aperture and the general form of the shell ; 

 characters in some instances difficult to define, but which strike the eye forcibly, and 

 from their constancy acquire specific importance. The general form of the shell in 

 M. hordeola is not so broad as that of M. eburnea, owing to the whorls being less 

 convex ; the spire is more obtuse, and comparatively shorter ; and the aperture is 

 longer and narrower, particularly at the posterior extremity, and it is more contracted 

 at the middle in consequence cf the greater involution of the outer lip. Other species 

 occur in the calcaire grossier, belonging to this group, and hitherto undescribed, but 

 which, as I learn from M. Deshayes, will be described in the forthcoming supplement 

 to his ' Description des coquilles fossiles,' &c. One of these {M. contabulata), appears 

 to be intermediate in size between M. eburnea and M. hordeola, and, in fact, to present a 

 close general resemblance to the former. It is unnecessary to enter upon any examination 





