70 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



PIUENOGAM^. 



GYMNOSPERMtE. 

 CYCADINEiE. 



The two essential groups of this family, the Zamiea and tlie Cycadeee, 

 have at our time a comparatively small number of species distributed in the 

 tropical and subtropical regions of the world. The genus Zamia is mostly 

 American, its species inhabiting Mexico, the West Indian Islands, and the 

 mountains of the Pacific coast; one species is found in Florida. Of Cycas, 

 no species is indigenous upon the American continent. 



In the old geological formation, the Cycadinece were very numerous, 

 especially most abundant in the Trias and the Oolite, which, taken both 

 together, have more than one hundred and sixty species of this order, out of 

 about two hundred, constituting the whole flora of this formation, as known 

 by authors. A number of vegetable remains from the Devonian and the Car- 

 boniferous, leaves known under the generic name of Flabellaria, Cordaites, 

 Nocggerathia; and fruits, Trigonocarims, Rhahdocarpus, Cardiocarpus, etc., are 

 until now of uncertain relation, some of their characters referring these plants 

 to this family, others to the Conifers. Very few CycadinecR are known in forma- 

 tions above the Jurassic. One, Pteroplyllum, is described from the Cretaceous 

 of Kansas, and another, closely allied, from that of Germany. This formation 

 has also two Strobiles described as Zamiostrobus; a third is known from the 

 Miocene. 



ZAMIE^. 



ZAMIOSTROBUS, Endl. 

 Zamiostrobus! mirabilis, Lesqz. 



Plate LXIII, Figs. 1-1 d. 



ZamiostroiHS mirabilis, Lesqx., Annual Report, 1874, p. 309. 



Fragment of a large silicified cone, checkered upon its onter surface by the rhomboidal obtuse top 

 of quadrangular long seeds, black-colored, and apparently of a hard substance, embedded into a white 

 celluloso-vascular matrix, separated from the common cylindrical axis by a zone of the same matter, or 

 fixed upon it by their base. 



The specimen represents a fragment only of the cross-section of a large 

 cone, measuring about fourteen centimeters in diameter, and perfectly silici- 

 fied. As seen in fig. 1, it is composed of a cylindrical axis, c, made up of frag- 

 ments of a dark opaque matter, agglutinated and amorphous, to which are 



