8 PEOCEEDINGS OF THE jSTATIONAL MUSEUM vol. 73 



the adjacent lobes being inequilaterally cuneate. Lateral sinuses 

 similar but only about half as deep. The small sinuses dividing the 

 lateral lobes into two unequal lobules narrow, acutely pointed, and 

 shallow. Stipe flat, with broad band of aggregated vascular bundles 

 down the middle ; length, 1.3 centimeters. Lamina ranging in length 

 from 1.25 to 2 centimeters in length and from 1.75 to 3 centimeters, 

 in maximum width. Texture subcoriaceous. Venation dichotomous, 

 diverging as a double dichotomy in the decurrent base of the lamina, 

 forking successively as shown in Figure 6. The veins are relatively 

 stout but have the appearance of being immersed in the substance 

 of the lamina. None of the specimens are distinctly fertile, but in 

 places the distal margin shows a decidedly thickened carbonized 

 border, as shown in Figure T, which may represent fructifications. 

 Some probability is furnished this interpretation, since no such 

 thickening is shown along the distal margin of the upper right-hand 

 lateral lobe. In most of the specimens the distal margins are more 

 or less frayed and do not permit any checking of these features^ 

 which, while not exactly as in living Adiantwrid, are suggestively 

 similar. 



The genus contains upwards of 100 widely distributed existing" 

 species in the warmer parts of the world and extending southward 

 to Chile, Paraguay, and Argentina, in some cases {A. concirmuTn 

 Humboldt, Bonpland, and Kunth) over nearly 40° of latitude, so 

 that they can not be said to be especially influenced by temperature 

 differences. In general, the existing species are less lobate and 

 less equilateral than the fossil, but in the absence of more repre- 

 sentative material showing pinnules from different parts of a frond 

 the validity of these apparent differences can not be evaluated. 

 About a score of Cretaceous and Tertiary species have been referred 

 to AdAantvmh^ including the quite dissimilar Adiantites borgdnianu 

 Engelhardt ^ from the Miocene of Lota, Chile. Among somewhat 

 similar existing species the following may be mentioned : Adiantum 

 chilense Kaulfuss of Chile, A. pensile Kunze of Brazil, A. teneruni 

 Swartz of Mexico and the Antilles to Peru, and A. coneirmutn 

 Humboldt, Bonpland, and Kunth which ranges from Central America 

 to Chile. Perhaps as similar a recent form as any is the old world 

 Adianitwm capillus-veneris of Linnaeus. 



Occurrence. — About 3 miles north of Estancia Chalia, Rio Chalia, 

 Territory of Santa Cruz. 



Holotype amd pamtypes. — Cat. No. 37852, USNM. 



'Engelhardt, H., Abh. Senck. Naturf. Gesell., vol. 16, Heft 4, p. 644, pi. 2, figs. 6-9, 

 1891. 



