TO JUNCTION OF GRAND AND GREEN RIVERS. 143 



lines long, rounded or subacute at extremity, very slightly constricted at base; 

 nerves fine, parallel, scarcely visible ; rachis strong, chaffy. 



In the form and attachment of the pinnules, this species approaches those grouped 

 by Fr. Braun under the name of Ptewsamites, in which the pinnules are usually 

 linear and obtuse, and are attached to the rachis by the entire breadth of the base, 

 which is not constricted. In the upper pinmiles of our plant, however, the bases are 

 very distinctly narrowed, and the attachment is sensibly oblique. 



There is no described species of Zamitcs for which this will be likely to be mis- 

 t;iken, nor does it clearly fall into any of the groups of the genus which have been 

 established. With the lance-leaved species (Podozamitcs Fr. Braun), such as Z. din- 

 tans, Z. lanccolatus, Z. loididatos, Z. falcatus, &c., it seems to have very little in common, 

 while from the group represented by Z. Fcnconis, Z. pectinatus, Z. Taxinus, &c. 

 (Pteroxamites Fr. Braun), in which the folioles are inserted by all their uncontracted 

 bases, it is separated by the slight though distinct expansion and 'constriction of the 

 bases of the leaves. It would, therefore,-seem to be a sort of connecting link between 

 the groups with auricled and those with simple folioles. It approaches, however, 

 nearest to that group of species described by Goeppert and Dunker (Z. Dunkerianum 

 Gopp, Z. Humboldtianum, Dunk., Z.^ Lydlianiim Dunk., &c.) from the Wealden, 

 included by these authors in Pterophyllum, but by Brongniart in Zamites, and perhaps 

 nearest of all to Ptcr. Saxonlcum, Reich. (Gaea, v. Saxon., p. 134, t. 4, f. 14; 

 Gopp., "Flora des Quadersandsteins in Schlesien", in Nova Acta Acad. Leop. Carol. 

 Ca?s. Nat. GUI-., Oct., 1847, p. 362, taf. xxxviii, fig. 13), from the Quadersandstone 

 (Cretaceous) of Saxony. 



Formation and locality. Top of Triassic series; Copper-mines near Abiquiu, New 

 Mexico. 



PECOPTERIS BULLATUS, Bunbury. 



Plate VI, figs. 1, 1". 



Among the specimens collected by Mr. Remond at Los Bronces, Sonora, are 

 several of a Pccopteris in fruit, which is apparently identical with that first described 

 by Bunbury from the coal-strata of Richmond, Virginia, and subsequently found by 

 Professor Emmons in North Carolina. This species is considered by Professor Heer 

 as identical with Pecopteris Stutgardtensis, Brong., one of the most characteristic 

 plants of the European Trias. 



Without more material, it woidd be presumption to attempt to decide this question ; 

 but that the plant before us is identical with that found in the Triassic strata of 

 Virginia and North Carolina there is little doubt, and it therefore becomes an impor- 

 tant connecting link between the eastern and the western exposures of Triassic, strata, 



Formation (Did locality. Triassic rocks; Los Bronces and on Yaki River 

 Sonora (Messrs. Remond and Hartley). 



PECOPTKRIS MEXICANA, Newb. 



Plato VI, figs. 9, 2. 



Frond bi- or tripinnate, small; pinna; elongated, narrow, linear, acute; pinnules 

 ovate, acute or subacute, sometimes falcate ; nervules delicate and few, simple or 



