Maryland Geological Survey 439 



similar to those sent off pinnately and alternately lower down; leaves 

 very thin and scale-like, elliptical, rhombic, or oblong, with varying age 

 changing their shape, the rhombic forms representing the oldest and 

 most crowded leaves, slightly keeled on the back, spirally arranged/' 



The only qualification that it is necessary to make in the foregoing 

 description is that referring to a single, smooth, bony seed under each 

 cone-scale. The present writer has been entirely unable to verify this 

 feature in any of the material some of which, however, suggests such 

 a seed habit. The cones are of small size and comparable to the cones 

 usually referred to Sequoia, i. e., with wedge-shaped peltate scales. The 

 material is all poorly preserved and the leafy twigs have evidently suf- 

 fered greatly from decay before fossilization. 



The genus may be distinguished from ArtJirotaxites TJnger,^ Echinos- 

 trohus Schimper,^ and Cyparissidium Heer,^ all of which have very similar 

 leafy twigs, by the characters of the cones, which are quite different. The 

 first two are Jurassic while the last extends from the Ehsetic to the 

 Upper Cretaceous. As a rule the twigs of Arthrotaxopsis are more elon- 

 gated and slender than those of these other genera, indicating beyond 

 doubt a pendulous habit. 



As originally described Arthrotaxopsis contained four species. Two 

 of these prove to be identical with the species described below while the 

 third was composite and included specimens of both Sphenolepis Kur- 

 riana (Dunker) Schenk and Sequoia ambigua Heer. 



Arthrotaxopsis expansa Fontaine 

 Plate LXXIV, Fig. 1 



Arthrotaxopsis expansa Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 241, pi. cxiii, figs. 5, 6; pi. cxv, fig. 2; pi. cxvii, fig. 6 (non pi. 



cxxxv, figs. 15, 18, 22 which are referred to Sphenolepis Kurriana 



(Dunker) Schenk). 

 Taxodium expansum Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 252, pi. cxxiii, fig. 1. 



^ Unger, Bot. Zeit., 1849, Nr. 19. 



^ Schimper, Pal. Vgg6t., tome ii, 1870, p. 330. 



' Heer, Fl. Foss. Arct., Bd. iii, Abth. ii, 1874, p. 74. 



