160 



SHOETER CONTRIBUTIONS TO GENERAL GEOLOGY, 1921. 



Tliis is a species oi great geologic range, 

 being recorded from the Jurassic to the Upper 

 Cretaceous. The geographic range is equally 

 extensive, embracing two continents, North 

 America and Europe. It is f|iiite [)robable 

 that the species is composite, but no certain 

 grounds for segregation are apparent. 



Some students may doubt the wisom of cor- 

 relating both Lower and Upper Cretaceous 

 forms with a species wliich is essentially a 

 Jurassic type, but specific differentiation found- 

 ed merely upon stratigraphy has gone astray 

 so often that in cases like the present syn- 

 thesis may well precede analysis, antl it might 

 be added that this was the view taken by Hol- 

 lick'^ with leference to material from Glen 

 Cove, Long Island, and by \'elenovsky '^ in 

 studying the Cenomanian Ikira of Bohemia. 



p^)rms indistinguisha])le from the type of 

 this species occur in both the Patuxent and 

 Patapsco formations of the Potomac group, as 

 well as in the Kootenai, Dakota, Black Creek, 

 Raritan, and Magotlw formations. 



Phylum CONIFEROPHYTA. 

 Genus BRACHYPHYLLUM Brongniart. 

 Brachyphyllum macrocarpum formosum Berry. 



Plate XXXVI, fit;uic 1. 



Brachi/iilu/llum iitucrocarpum Berry, Torrey Hot. Club Bull., 



vol. ;iS, ]>. lS:i, 1910 mot Newberry, J.'^OOi; vol. 38, 



p. -120, itni. 

 Bmchijphi/lhiin itiiiirocdrpum formosum lierry, idem, vol. 



39, p. 392, pi. 30, 1912; U. S. (ieol. Survey Prof. 



Paper SI, p. 100, 1904; Prof. Pajier 112, ]>. 59, pi. 5, 



fig. 9, 1919. 



Slender elongated twigs, pinnately branched, 

 covered with medium-sized crowded, appressed 

 leaves, spirnlly arranged. Leaves bluntly 

 pointed, smooth, thick. 



In the consideration of the various specunens 

 which have been referred to Brachyphj/JIum 

 macrocarpum, a very considerable variation 

 within certain fixed limits is at once obvious. 

 This variation is usually one of size, the more 

 slender si)ecimens being* at the same time 

 smoother. This characteristic has l)eon fre- 

 (|iK'ntly noted by me and is commented upon 

 in jjrint by Knowlton," who in discussing the 



" Hollick, Arthur, U. S. Geol. Survey Mon. .ill, p. 3.5, 191)6. 



'3 Veleiiovsky, Josef, Die Gyimiospennen der buhraischen Kreide- 

 formation, p. II, pi. 2, figs, ll-m, 24, ls.\5. 



■< Kuowltou, F. H., U. S. Geol. Survey Bull, lia, p. 2D, pi. 4, figs. 5, 6, 

 1900. 



younger forms from Wyoming suggests that the 

 species on the verge of extinction became smaller 

 in its proportions. In studj'ing the material 

 from the South Atlantic and Gulf States a con- 

 stant difference in size was noticed. This may 

 reflect a slight difference in climatic condi- 

 tions, and all the forms may be interpreted 

 as the variations of a single species — in fact, 

 the specimen from the Raritan formation in 

 New Jersey illustrated in Newberry's figure 

 7 '^ is approximately of the same size as the 

 forms from the Montana group of the West 

 and is associated with the normal stout, club- 

 shaped type. That the variety has no par- 

 ticular stratigraphic significance is indicated by 

 its abundance at a horizon as low as the basal 

 part of the Tuscaloosa of Alabama and its 

 presence in the Woodbine sand of Lamar 

 County, Tex. In general the present variety 

 occurs in later and more southern beds than the 

 type, a difl'erence which might l)e ascribed to the 

 fact that only the slender terminal twigs are 

 preserved. This explanation is regarded as 

 improbiible, however, for the same reasoning 

 should hold good for the areas where only 

 tliicker twigs have been found. 



The remains are usually much macerated 

 and broken, and the immediate cause for the 

 recognition of a new variety was the discovery 

 of a relatively large specimen from the ilagothy 

 formation of Maryland, wliich showed such 

 strikmg unlikeness to the type that separation 

 was demanded and specific differentiation was 

 even considered. In view, however, of the 

 occurrence of l)oth forms in association in 

 Maryland and the well-loiown variation not 

 only of the type but of coniferous foliage in 

 general, it seemed wiser to consider the present 

 form as a variety of the type, which as time 

 progressed supplanted it to si large extent if not 

 altogether. 



The new specimen from Marylantl showed 

 the terminal part of two approximately 

 parallel and curvetl twigs about 12 centimeters 

 in length, united proximad. These in their 

 largest portion are only 6 milhmetors in chame- 

 ter. At intervals of 3 to 5 millimeters sub- 

 opposite lateral branches are given off in a 

 pimiate mamier. These are relatively much 

 elongated, curved, and slender, averaging 

 about 4 centimeters in length by 2 millimeters 



1' Newberry, J. S., U. .S. Geol. Survey Mon. 25, pi. 7, figs. 1-7, 1S96. 



