no. 1821. REVISION OF POTOMAC PLANTS— BERRY. 309 



exactly similar remains of leaf-bearing twigs bore cones which are 

 unquestionably those of a Sequoia. Twigs of this sort are abundant 

 throughout the Potomac group, occurring also in the Fuson formation 

 of the Black Hills, the Kootanie of Montana, the Shasta of California, 

 the Koine beds of Greenland, and the Neocomian of central Mexico. 

 Abroad they have been reported from the Upper Jurassic (?) of Por- 

 tugal, the Neocomian of Belgium, the Urgonian of Silesia, and the 

 Gault of Switzerland. Similar remains have also been described from 

 a large number of horizons in the Upper Cretaceous, both in this 

 country and abroad. 



The slight variations from specimen to specimen and the varying 

 conditions of preservation in the twigs of this species throughout the 

 Potomac deposits, together with the detached and more or less mace- 

 rated cones, furnished the basis for six species and varieties of Fontaine 

 and Ward, but these are obviously not specifically distinct from one 

 another. 



Occurrence. — Patuxent formation : Fredericksburg, Lorton (Tele- 

 graph Station), and Dutch Gap, Virginia; Springfield, Maryland. 

 Arundel formation: Reynolds Ore Pit, Maryland. Patapsco 

 formation: Near Brooke, Virginia,. 



Collections. — U. S. National Museum. 



SEQUOIA RIGIDA Heer. 



Sequoia rigida Heer, Flora Foss. Arct., vol. 3, pt. 2, 1873, pp. 80, 91, 102, 128, 

 pi. 22, figs. 5g, 11a; pi. 25, fig. G; pi. 27, figs. 8-14; pi. 38, figs. 9a, 10.— 

 Schenk, Palaeontographica, vol. 23, 1875, p. 168, pi. 29, figs. 8, 9. — Heer, 

 Flora Foss. Arct,, vol. 6, pt. 2, 1S82, p. 52, pi. 7, figs. 10-12; pi. 8, fig. 7; pi. 

 11, fig. lc; pi. 24, fig. 36; vol. 7, 18S3, p. 13, pi. 53, figs. 5-7.— Fontaine, 

 Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 246, pi. 118, fig. 3; pi. 121, fig. 

 2; pi. 126, fig. 3; pi. 130, fig. 3. — Knowlton, in Stanton and Marl in, Bull. 

 Geol. Soc. Amer., vol. 16, 1905, p. 408.— Fontaine, in Ward, Monogr. U. S. 

 Geol. Surv., vol. 48, 1906, p. 219. 



Sequoia subulata Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, 245, pi. 117, 

 fig. 7; i)l. 118, figs. 5, 6 (not Heer). — Fontaine, in Ward, Monogr. U. S. Geol. 

 Surv., vol. 48, 1906, pp. 486, 571 (not Heer). 



Description. — This species was described by Heer from the Kome 

 beds of Greenland, although he subsequently pointed out that it was 

 more abundant in the Atane beds. He compares it with Sequoia 

 woodwardii (Carruthers) Schimpcr of the upper Greensand of England 

 and with Sequoia pectinata Heer of the Senonian of Germany. It 

 is also recorded from the Gosau beds of Europe and from the Upper 

 Cretaceous of Alaska as well as from the Potomac of Virginia, the 

 Kootanie of Montana, and the Shasta of California. The specific 

 identity of these Upper and Lower Cretaceous forms may well be 

 doubted, but no clear line of demarcation can be drawn between them 

 at the present time. It is quite possible that the Potomac forms are 

 merely variants of the abundant Sequoia reiclienbachi, since they fail 

 to show the transverse rugosity (a feature of the preservation merely) 



