Published in Proc. Acad. Nat. Sci. Philadelphia, in 1900, in volume 52, pages 151-159

Published in Proc. Acad. nat. Sci. Philad., in 1900, in volume 52, pages 529-543

Published in Proceedings of the Academy of Natural Sciences of Philadelphia, in 1900, in volume 1900, pages 431-433

Published in Proceedings of the Academy of Natural Sciences of Philadelphia, in 1900, in volume 1900, pages 426-430

Published in Proceedings of the Academy of Natural Sciences of Philadelphia, in 1900, in volume 1899, pages 473-474

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 772-773

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 385-394

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 381-384

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 544-549

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 582-611

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 613-622

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 460-463

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 339

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 779

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 449-459

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 763

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 160-338

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 755-759

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 684

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 87

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 482-490

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 464

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 74-86

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 556-560

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1900, in volume 52, pages 561-567