E. D.  Cope, ?Report on the reptiles brought by professor James Orton from the middle and upper Amazon and western Peru.?, Journal of the Academy of Natural Sciences of Philadelphia, new series, vol. 8, pp. 159?183, 1875.

E. D.  Cope, ?On the batrachia and reptilia of Costa Rica.?, Journal of the Academy of Natural Sciences of Philadelphia, new series, vol. 8, pp. 93?154, 1875.