CAEDIUM CEEBRIECHINATUM. 49 



ment in outline between the casts and his figure, taking the side view, that 

 the propriety of referring the fossils to the species named above is manifest. 

 But the figure must have been drawn from a cast on which the ridge caused 

 by the filling of the posterior gape of the valves had been worn away. This, 

 as seen in our figure, presents at the margin a straight line running obliquely 

 downward from the obtuse angle which it forms with the hinge line. The 

 posterior view shows curved grooves proceeding from the beaks downward 

 and inward to the mesial ridge. These are imprints left by internal umbonal 

 ridges, such as occur in the recent C. comors Sow., C. isocardia, Linn., and other 

 species of the subgenus Acanthocardia, which ridges stamp upon plaster casts 

 of their interiors like grooves, but less deeply impressed. The species just 

 named, however, have no defined lunule, but their internal casts show be- 

 neath the beaks, in front, a widely cordate impression, left by the large 

 anterior lateral teeth. The corresponding cavity in the Lebanon casts is 

 due to a like cause, and outside of it is seen the border of a " lunule large 

 and cordate," but very feebly impressed. Two of the casts clearly show the 

 presence of thick-set, narrow radiating ribs. Coll. Thomson and Merrill. 



Locality and Podiion. — Beirut district ; probably from the zone of the 

 Cardium bed. 



Cardium crebriechinatum Conrad 



Cardium crebriechinatum Coxead, 1852, OfEcial Report, pp. 217 and 231, PI. vi, figs. 41-13, PI. xt, fig. 77, 



and App., PI. ii, fig. 16. 



Two specimens, one Avith test, and nearly entire ; the other an imperfect 

 cast. 



Fraas doubts the classification of this species as a Cardium, and is inclined 

 to consider it to be a Cardita, — on what ground Is not evident. Lartet 

 thinks it may be Identical with C. sidcifenmi Coquand (Geol. et Paleont. de 

 Constantine, p. 206, PI. x, figs. 15, IG). The forms of the two .species are 

 Indeed very similar, and both are covered with radiating ribs; but upon 

 sidcifenmi (which is much the larger of the two) the ribs are wide, while 

 upon crebriechinatum they are much more numerous and very narrow. Coll. 

 Thomson. 



Localiti) and Position. — Found at Abeih by Fraas, and by him referred to 

 the Gasteropod zone of that vicinity. 



7 



