Pterygotus sp. 
1-4 Apparently distal portion of the female opercular appendage of a 
Pterygotus. Natural size 
5 Small, well preserved telson. Natural size 
6 Ultimate postabdominal segment. Natural size | 
7 Telson with distinct coarse marginal serrations. Natural size 
8 Fragment of appendage, apparently telson of an Erettopterus, with 
distinct marginal serrations and a peculiar ornamentation. Natural 
size | 
9 Fragment of segment with ornamentation suggestive of Pterygotus. 
Natural size 
Horizon and locality. Lower Siluric: Schenectady shale. The originals 
of figures 1-4 are from the Crumby quarry, Aqueduct, that of figure 
5 is from Duanesburg, those of figures 6-8 from the Dettbarn quarry, 
Schenectady and that of figure 9 from Rotterdam Junction. 
All originals are in the State Museum 
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