no. 1821. REVISION OF POTOMAC PLANTS— BERRY. 311 



Description. — Remains of the foliage of this species are distin- 

 guishable from those of contemporaneous conifers which occur in the 

 beds with them by the relatively short and very stout, acuminate, 

 falcate, or recurved, decurrent leaves. 



The cones are spherical and consist of relatively few short scales 

 with longitudinally striated peduncles and suddenly expanded, quad- 

 rangular, peltate, umbilicate tips. These cones are abundant in the 

 lower Cretaceous of Maryland, occurring usually as detached ferrugi- 

 nized mud casts. They vary considerably in size, and this has re- 

 sulted in their having been referred to two species and genera, the 

 smaller having been identified by Professor Fontaine as Arthrotaxop- 

 sis expansa, while the larger were referred to Sequoia ambigua. As 

 Professor Ward pointed out in his monograph, 1 they show no differ- 

 ences except in size, and even this feature has rather narrow limits 

 of variation with every gradation present. The writer has carefully 

 compared a large suite of specimens and many wax casts of the scales 

 and finds them absolutely identical in every respect, the relative pro- 

 portions 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. Described originally from the Kome beds (Urgonian) of Green- 

 land by Professor Heer, this author soon afterwards recorded it from 

 the Upper Cretaceous Atane beds of that country. It has been 

 recorded by Nathorst from the Neocomian of Mexico and it is present 

 in the Kootanie formation of Montana. It is a member of the Shasta 

 flora of the Pacific coast (Horsetown beds) and is probably repre- 

 sented in the Fuson formation of eastern Wyoming by what Profes- 

 sor Fontaine calls Sequoia gracilis. In the Upper Cretaceous, remains 

 in every way identical with these Lower Cretaceous occurrences are 

 present in the Magothy formation at Gay Head and at a number 

 of localities in Maryland as well as in the Tuscaloosa formation of 

 Alabama. 



In the Potomac group this species ranges from the base of the 

 Patuxent, through the Arundel to the top of the Patapsco often in 

 considerable abundance. Seward 3 comments on the resemblance 

 between Sequoia ambigua Heer and the widespread remains of Spheno- 

 lepis sternbergiana (Dunker) Schenk, a resemblance strikingly shown 

 in some Weal den specimens of the latter from Ecclesbourne recently 

 received by the writer. However, their preservation is not of the 

 best, and the English specimens seem to show slight differences from 

 the type of this species in the direction of what in America is iden- 

 tified as Sequoia ambigua. No changes in nomenclature are pro- 

 posed, however, since it seems probable that Sphcnolepis Sternberg- 



i Monogr. U. S. Geol. Surv., vol. 48, 1906. 2 Wealden Flora, pt. 2, 1895, p. 206. 



