PLANTS IKOM ALASKA. 157 



toward the ends of the ultiinalc piniue and -aw more and more united, 

 so that they pass to lobes and finally to teeth. The ol)li(|uity of insei'lion 

 of the pinnules makes the bases of the nltinialc |)iniKr wed^c^ sliapiMl. 

 Towai'd the termination of the comixjund |)imia, or fi'ond, the ultimat(> 

 pimue become redurecl to pimiules. In such parts the peiniltimate 

 pinna% now reduced to ultimate ones, are nuicli elon,u;at(Ml and toward 

 their ends have the pinmdes passin<i into lol)es and finally into teeth. 

 Toward the ends of the compound pinna the ultimate pimur become 

 reduced to elongate dentate pinnules. The same obli(juily. narrowness, 

 and acuteness are maintained in these transformations into loli(>s Mnd 

 teeth. The nervation can not be made out, as all the specimens ai'e 

 preserved in a sandstone. No fructification is sliown, and the plant nnist 

 be determined from the character of its sterile parts. It tliffers somewhat 

 from the character of Onijchiopsis psilotoidcs as given in most of the 

 specimens hitherto descriljed, l)ut the vai'iation does not api)eai- gi'eater 

 than the limits of the species. The variation is found in the facts that 

 the Alaskan fossil has the pinnules, lobes, and teeth more closely placed 

 than in most of the forms of 0. psilotoidcs and that the lamina^ of the 

 foliage is in greater proportion to the nervation. The crowding may be 

 due to a creep of the rock and to pressure, for these features appear in 

 the specimens. 



This plant resembles (). clongata (Geyl.) Yok., a Jurassic fossil, but 

 is more delicately incised. It probably lies between it and 0. psilotoidcs. 

 It is also near a number of fossils described in Monogr. XT. S. (Jeol. 

 Surv., Vol. XV (The Potomac or Younger Mesozoic flora). It especially 

 reseml)les Thyrsopteris angustifolia Font., the form given in Fig. 8 being 

 much like those depicted in that work on pi. xlv, fig. 3, and pi. xlviii, 

 fig. 2. But the pinnules and lobes of the Alaskan plant are more slender 

 than even these. 



Genus CLADOPHLEBLS Brongniart. 



Cladophlebis vaccensis Ward." 



PI. XXXIX, Figs. 7, N. 



1888. "i Pecopteris denticulata Ileer. Le.s(ni(M('ux: Proc. V. S. Nat. Mus., Vol. XI, 

 p. 32. 



On one of tlie rock fragments collected by Mr. Woolfe there is an 

 imprint of fern which has the Museum \o. 2526 and Professor Lesque- 



" See pp. 6f)-()S. 



