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DESCRIPTIONS OF NEW SPECIES OF FOSSILS, 



FROM THE HAMILTON GROUP OF WESTERN NEW-YORK, WITH NOTICES OF OTHERS 

 FROM THE SAME HORIZON IN IOWA AND INDIANA. 



LINGULA LIGEA (n. s.). 

 Shell narrow elliptical ; length equal to twice the width; sides regularly curving; 

 extremities subequal; margins of the valves thickened. Surface marked by fine 

 concentric striae, and by a few obscure or obsolete radiating striae. The more 

 convex valve shows, along the inner margin, a narrow shallow groove as if the 

 edge of the opposite valve closed just within its margin. 



The shell is of more equal width throughout and more symmetrically oval, and 

 is much larger than the L. spatulata of the Genesee slate. 



Geological formation and locality. In the shales of the upper part of the Ha- 

 milton group, on the shore of Seneca lake; and near the base of the Portage group, 

 at the falls below Trumansburgh, N.York. 



LINGULA PAL^FORMIS (n.s.)- 

 Shell broadly subovate, convex at the umbo a ad depressed below, the length a 

 little greater than the greatest width, rapidly expanding for about two-thirds 

 the length of the shell, below which it is abruptly rounded ; shell thick. Surface 

 marked by strong concentric lamellose strise, and, in the exfoliated surface, by 

 fine radiating striae. 



Geological formation and locality. In the shales of the Hamilton group, as- 

 sociated with numerous known fossils, in a loose fragment of rock in the valley 

 south of Cayuga lake. 



Fig. 1. Lingula palcBformis. 



Fig. 2. Lingula exilis. 



Fig. 3. Crania hamiltonicB; the dorsal valve adhering to Tropidolepus carinatus. 



Fig. 4 & 5. Crania hamiltonensis ; the interiors of ventral valves, showing some dif- 

 ference of form, and fig. 5 showing more distinctly the vascular impressions. 

 Fig. 6. Crania crenistria; the exterior of the dorsal valve. 

 Fig. 7. Crania leoni; the interior of the ventral valve in its natural proportions. 

 Fig. 8. Crania leoni; the interior of the ventral valve of a distorted specimen. 



