no. 1821. REVISION OF POTOMAC PLANTS— BERRY. 315 



Occurrence. — Patctxent formation: Dutch Gap and immediate 

 vicinity, Virginia; Patapsco formation: Brooke, Virginia. 

 Collections. — U. S. National Museum. 



ABIETITES LONGIFOLIUS (Fontaine) New Combination. 



Leptostrobus longifolius Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 

 228, pi. 101, figs. 2, 3; pi. 102, figs. 1-4; pi. 103, figs. 6-12; pi. 104, fig. 6.— 

 Fontaine, in Ward, 19th Ann. Rept. U. S. Geol. Surv., Pt. 2, 1899, p. 671, 

 pi. 163, fig. 15; pi. 165, fig. 3. — Fontaine, in Ward. Monogr. U. S. Geol. Surv., 

 vol. 48, 1906, pp. 281, 481, 482, 491, 506, 528, 551, 557, pi. 110, fig. 11; pi. 116, 

 fig. 1. 



Description. — Leaves long and narrow, needlelike, 10 to 15 cm. in 

 length, aggregated in bundles. Bundles apparently borne on short 

 shoots, with many leaves in each bundle. No satisfactory venation 

 can be made out. Fontaine describes a various number of veins in 

 these forms, but as nearly as can be determined these are simply folds 

 due to compression or simply the angles of the leaf. 



This species has a considerable geologic as well as geographic range, 

 having been recorded from the Kootanie formation of British Colum- 

 bia and the Fuson formation of the Black Hills. In the Potomac 

 group it is of frequent occurrence and individually common, being- 

 found in the oldest as well as the youngest beds. The remains are 

 always poorly preserved and were evidently much macerated before 

 fossilization. They are closely comparable with Pinites solmsi 

 Seward of the Wealden and with Pinus peterseni Heer from the Kome 

 beds of Greenland. They may also be compared with the genus 

 Prepinus proposed by Professor Jeffrey for certain structural material 

 from the Upper Cretaceous. 



The genus Leptostrobus was proposed by Heer 1 in 1876 for certain 

 Siberian Jurassic cones, although in 1880 remains of foliage were also 

 correlated with these cones. 2 Five species in all were described. 

 The age of the containing beds is Oolitie. Subsequently this generic 

 name was utilized by Ward and Fontaine for a considerable number 

 of American Jurassic and Cretaceous species, based on an assort- 

 ment of probably unrelated vegetative twigs, supposed cones, and 

 seeds or fruits. 



Occurrence. — Patuxent formation : Fredericksburg, Potomac Run, 

 and Dutch Gap, Virginia ; Patapsco formation : Brooke, 72-mile post, 

 Mount Vernon and Hell Hole, Virginia; Fort Foote, Vinegar Hill 

 (very common), and Federal Hill (Baltimore), Maryland. 



Collection. — U. S. National Museum. 



THE GENUS PINUS. 



Modern members of this genus are the dominant conifers of the 

 northern hemisphere with about 70 species, usually forming vast forest 



' Heer, Flora Foss. Arct., vol. 4, Abth. 2, 187C, p. 72. 2 Heer, Idem., vol. 6, Abth. 1, 1880, p. 23 



