PORTAGE GROUP. 
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In the Cashaqua shale, or lower member of this group, there are several species of shells 
which have not been seen in any other rock, and at the same time there are no fossils found 
with them which are known in other rocks beyond the group. 
The following woodcut presents the more common forms : 
106 . 
1. Avicula speciosa. 4. Orthoceras aciculum. 
2. Ungulina suborbicularis. 5. Clymenia? complanata. 
3. Bellerr.phon expansua. 6. Goniatites sinuosus. 
7. i’innopsis acutirostra. 
8. Pinnopsis ornutus. 
1. Avicula sjpeciosa, n. s. — Semioval or semicircular ; hinge line straight, extended beyond 
the width of the shell, and angulated at either extremity ; surface marked by about ten ribs, 
which are crossed by beautifully curved concentric lines. 
1 a. A specimen presenting both valves, attached at the hinge. This is not an unusual 
condition of this fossil. 
The shell is usually very minute ; its markings are very beautiful, and easily recognized. 
It is quite abundant in the Cashaqua shale, and alone seems sufficient to identify the mass. 
Locality —Cashaqua creek ; Genesee river ; Penn-Yan; Eighteen-mile creek. 
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