LAMELLIBRANCHIATA. 16 



smaller intermediate implanted rays, crossed by fine, regular, elevated Bharp 

 lines of growth, which ;it intervals are raised into lamella?, and appear in tin- 

 cast as strong transverse ridges crossing the radii. The furrows between the 



radii are narrower than the rays. The regular alternate I' the radiating 



lines where seen is a very conspicuous feature. The righl valve is marked 

 by more numerous and subdued rays, and their alternation is somewhat 



obscure. The ears show line radiating lines and stronger and more crowded 



concentric striae. 



The differences between the righl and left valves, arc the convexity, the 



surface markings, and the deep byssal -inns of the righl valve. 



The characters of the interior are not known. 



A medium-sized individual has a height of 17 nun., longitudinal diameter 

 •>4 nun., binge-line 32 nun. A. smaller specimen measures in height •'!•"> nun.. 

 length -'IS nun., hinge-line -4 mm. 



The largest specimen (imperfect) shows a heighl of 74 nun., and a length 

 of SS mm. 



In outline and general aspect this species closely resembles L. macrodontus 

 (plate S, figs. '.•, Hi), hut differs in the obliquity of the beak, wider anterior 

 ears, and more elevated and numerous rays. It differs from L. magnijicus in 

 its outline, larger anterior ears, longer binge-line, and liner radii of the ears. 



The anterior cars of this species, and also of L. solox and L. polydorus, arc 

 smaller than in the species referred to A.VICULOPECTEN. 



The specimens mostly preserve both valves iii connection. A large specimen 

 (plate 82, fig. 5), occurring in the barder argillaceous sandstone, attains nearly 

 the dimensions ofZ». cymbalon (plate 24, fig. 8), but differs conspicuously in the 



more numerous, Btrong radii, their gentle curvature toward the anterior side, 

 ami the smaller area of surface upon the anterior Bide of the vertical axis of 

 the valve. 



Formation and local it ij. In the shales of the Hamilton group, Fultonham, 



Schoharie count \ . X. Y. 



