30 SYEIAN MOLLUSCAX FOSSILS. 



prope rectum, rejiexum, edentidum, ad margincm anteriorem effusum et incrassutmn, 

 postice temdssimum ; labrniii Icnue. 



Shell ovately cylindrical, apparently rimately perforate : spire rather pro 

 ducecl and with an acute apex: whorls about six, flatly convex; the body- 

 whorl very large and three times as long as the spire ; suture impressed : 

 surface marked with striaj of growth, of which some are quite heavy : aper- 

 ture elongate, narrowed to a sharp termination behind, in front rather wide 

 and rounded; inner lip nearly straight, spread upon the body wall, without 

 folds, at the front eftlise and thickened, while posteriorly it is very thin ; 

 labrum thin. 



Single specimen, with test. Length, 35J mm. ; width, \%\ mm. 



The combination of characters indicates this to be a genuine Adceonina ; 

 viz. the relative proportions of the spire and body-whoi'l ; the inner lip, before 

 flatly thickened at the edge and neither plicated nor twisted ; the aperture 

 evenly rounded in front and sharply angled behind; tlie last whorl anteriorly 

 somewhat suddenly contracted. Yet the iimer lip, conspicuously spread 

 upon the body-whorl through the whole length of the aperture, and the 

 apparent rimate jierforation of the columella, distinguish this from any other 

 species of the genus which has been hitherto figured. The seeming, and 

 probably real, perforation is the continuation of a pit formed by an unusual 

 projection of the thickened edge of the inner lip over the concave part of 

 the narrowed front of the body-whorl. It resembles the rimate umbilicus 

 of some species of Bidnnidus. 



In the published figures of Adwoniiia oUvcrformis Koch and Dunker, the 

 species most like this, good front views are wanting, perhaps from imper- 

 fection of the specimens delineated. The back of oUvccformis, as figured by 

 Morris and Lycett (Moll. Gr. Ool., PI. xli, figs. 4, 4 a), sufficiently resembles 

 that of our specimen to allow the two to be regarded as specifically identical. 

 But Morris and Lycett's figure of the front (Ibid., PI. viii, fig. 14), and Koch 

 and Bunker's figures of both back and front (Norddeutschen Oolithgebildes, 

 PI. V, figs. 3 a, h), do not agree with the Lebanon fossil. Moreover, no ade- 

 quate description of olivafornih exists, since the original one by Koch and 

 Dunker (Ibid., p. 41, 1837) is brief and meagre, while Morris and L^'cett 

 (op. cit., Pt. I, p. 103) have simply copied it without additions. It has 

 therefore seemed best, provisionally at least, to describe the Lebanon shell 

 as a new species. Coll. Bird. 



Localily and Position. — Abeih ; from the more arenaceous portion of the 

 Turonian yellow marl. 



