450 Systematic Paleontology 



Sphenolepidium dentifolium Fontaine, 1906, in Ward, Mon. U. S. Geol. 



Surv., vol. xlviii, 1905, pp. 484, 528, 538, 546, 555. 

 Arthrotaxopsis expansa Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., vol. 



XV, 1889, pp. 533, 535, 538, 555, 573, pi. cix, figs. 12, 13 (non pp. 504, 



520, 547, 571). 

 Sequoia amtigua Hollick, 1907, Mon. U. S. Geol. Surv., vol. 1, p. 41, pi. iii, 



figs. 7, 8. 

 Sequoia amtigua Knowlton, 1907, Smith. Misc. Coll., vol. iv, pt. i, 1907, 



p. 126. 

 Sequoia ambigua Berry, 1910, Bull. Torrey Club, vol. xxxvil, p. 20. 

 Sequoia ambigua Berry, 1911, Proc. U. S. Natl. Mus., vol. xl, p. 310. 



Description. — " S. ramis elongatis, foliis omnino tectis, ranmlis alter- 

 nis, gracilibus, foliis decurrentibus, brevibus, crassiuseulis, falcato- 

 incurvis, apice acuminatis, uninerviis, strobilis globosis, squamis peltatis, 

 planiusculis." — Heer^ 1874. 



Eemains of the foliage of this species are distinguishable from those 

 of contemporaneous conifers, which occur in the beds with them, by the 

 relatively short and very stout, acuminate, falcate or recurved, decur- 

 rent leaves. 



The cones are spherical and consist of relatively few short scales with 

 longitudinally striated peduncles and suddenly expanded, quadrangular, 

 peltate, umbilicate tips. These cones are abundant in the Lower Cre- 

 taceous of Maryland occurring usually as detached ferruginized mud- 

 casts. They vary considerably in size and this has resulted in their 

 having been referred to two species and genera, the smaller having 

 been identified by Professor Fontaine as Arthrotaxopsis expansa while 

 the larger were referred to Sequoia arnbigua. As Prof. Ward pointed 

 out in Monograph XLVIII they show no differences except in size, and 

 even this feature has rather narrow limits of variation with every grada- 

 tion present. The writer has carefully compared a large suite of speci- 

 mens and many wax casts of the scales and finds tbem absolutely identical 

 in every respect, the relative proportions of the scales from the smallest 

 and the largest cones giving the same ratios of length, width, and height. 



As recorded in the literature cited above Sequoia ambigua is widely 

 distributed geographically and it has an equally great geological range. 



