Spieker, E. M., 1922. The Paleontology of the Zorritos Formation of the North Peruvian Oil Fields. Johns Hopkins University Studies in Geology, 3: 1 -196 . (3.36 MB)
New Species-Group Names:
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berryi Spieker, 1922. p. 39. pl. i. f. 4.
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bocapanensis Spieker, 1922. p. 38. pl. i. f. 3.
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bravoi Spieker, 1922. p.41. pl. i. f. 6.
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cacuminatus Spieker, 1922. p. 40. pl. i. f. 5.