GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 33 



extended. Base very inequilateral, truncate or ascending on one 

 side and wide and cordate on the other. Margins entire, full. Tex- 

 ture subcoriaceous. Length about 8 cm. or 9 cm. Maximum width, 

 at or slightly above the middle, about 4 cm. Petiolule curved, short 

 and stout, about 3 mm. long. Midrib stout, greatly curved. Sec- 

 ondaries thin, five or six pairs, angles of divergence and courses 

 various, all ultimately camptodrome ; lower pair opposite, from the 

 top of petiolule ; they diverge from the midrib at angles of about 45 

 degrees, curving slightly outward and then ascending, parallel with 

 the respective margins; the one in the narrow side of the lamina 

 arches along the margin in a brochiodrome manner; the one in the 

 wide side of the lamina sends off on the outside a series of regularly 

 spaced camptodrome tertiaries. Tertiary venation for the most 

 part obsolete. 



This characteristic species may be compared with Inga densiflora 

 Bentham, 1 Inga edulis Martius, 2 Inga marginata Willdenow, 3 or Inga 

 speciosa Spruce * and with various other of the larger-leafed species 

 of Inga in the American Tropics to which region the 212 of its 

 existing species of shrubs and trees are confined. It may also be 

 compared with a number of tropical American species of Cassia, as, 

 for example, Cassia ruseifolia Jacquin. 



About fiften fossil species have been referred to Inga. These 

 include three from the Upper Cretaceous, two European, and one 

 North American. There are also two or three species in the Oligo- 

 cene of Europe, one in the Pliocene of Bolivia, two in the Tertiary 

 of Ecuador, and one in the Tertiary of Colombia, four well-marked 

 species in the Lower Eocene of the Mississippi embayment (Wilcox 

 Group) and one in the middle Eocene of that region (Claiborne 

 Group). The Panama species is not especially close to any of the 

 foregoing. It is nearest, however, to Inga latifolia, described by 

 Engelhardt 5 from the Tertiary of Ecuador, differing in its broader 

 form and more inequilateral base. 



Pittier records 14 existing species of Inga, from Panama. 6 Hems- 

 ley lists 35 species in his flora of Central America, or which number 

 18 are recorded from Panama. 



Occurrence. — Lower part of Culebra beds one-fourth mile south of 

 Empire Bridge. (Collected by D. F. MacDonald.) U.S.G.S. 6837. 



Type.— Cat. No. 35311, U.S.N.M. 



1 Bentham, Trans. Linn. Soc. Lond., vol. 30, p. 617, 1875 (Peru). 



2 Martius, Flora, vol. 20, Beibl., p. 113. 1837 (Brazil). 



3 Willdenow, Sp. PI., vol. 4, p. 1015, 1806 (Venezuela). 



* Spruce, in Bentham, Trans. Linn. Soc. Lond., vol. 30, p. 620 (Brazil). 



5 Engelhardt, H., Abh. Senck. Naturfor. Gesell., vol. 19, 1895, p. 20, pi. 2, figs. 11, 12. 



« Pittier, H., Cont. U. S. Natl. Herb., vol. 18, pt. 5, pp. 218-223, 1916. 



