344 Systematic Paleontology 



bord de la foliole, et par consequent convergentes vers le sommet; fines 

 et egales entre elles, tres rarement bifurquees lorsque la foliole est elargie 

 dans sa partie moyenne." Braun's genera Podozamites and Pterozamites 

 were included as subgenera. 



Zamites has been redefined by various subsequent authors notably 

 Bornemann/ Saporta/ Schimper/ Schenk/ Seward/ etc., and it will 

 suffice in this connection to quote the definition of the latter author, 

 which is as follows : " Frond pinnate, pinnge more or less obliquely in- 

 clined to the racliis and attached to the upper surface, apices acuminate 

 and tapering or obtusely rounded, the base may be abruptly rounded and 

 marked with a callosity near the point of attachment, or the pinnge may 

 be slightly and gradually narrowed towards the base, margins entire; 

 veins parallel, but slightly divergent in the apical portion of each pinna." 

 While the foregoing characterization is quite general, greater precision 

 seems undersirable in the present case. 



The basal callosity, a feature emphasized in most definitions, is a 

 character the determination of which is often exceedingly difficult in the 

 best of fossil material, and, of course, impossible in fragments of pinnae 

 which lack the base. Although Fontaine and Ward have described seven 

 species of Zamites from the Potomac Group, this proves to be much too 

 large a number, only two species being recognized in the present work. 

 These, while not common, are found at various horizons, always de- 

 tached, however, and generally fragmentary, so that their distinctness 

 from pinnse of Podozamites is often determined with difficulty. 



The genus has a recorded range from the Triassic to the Oligocene, 

 with many species in the Mesozoic, and while all of the species are not 

 congeneric botanically, they are all doubtless referable to the Cycad- 

 ophytse. 



^ Bornemann, Ueber organische Reste Lettenkohlen Gruppe Thuringens, 

 1856, p. 54. 

 ^ Saporta, PL jurass., tome ii, 1875, p. 84. 



* Schimper, Pal. Veget., tome ii, 1870, p. 151. 



* Schenk, in Zittel, Handbuch, 1890, p. 218. 

 = Seward, Wealden Fl., pt. ii, 1895, p. 75. 



