Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1891, in volume 43, pages 56-61

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Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1891, in volume 43, pages 73-74

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Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1891, in volume 43, pages 120

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Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1891, in volume 43, pages 342-388

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