2L)-2 MESOZOR' floras of I'MTED STATES. 



forms as Podozamites lanceolnius (L. & H.) Fr. Br. fi-oin the Jurassic 

 of Oroville, California; P. laticeolatus lafifolms (Fr. J^r.) Iloor, or 

 P. Emmonsii Xewb., from the Trias of Xortli Carolina." 



PI. LXII, Figs. 1-3, PI. LXIII, Fig. 1, Cijcadella ramentimi Ward; 

 PI. LXII, Fig. 4, Williamsonia gigas (L. & H.) Carr. 



PI. LXII. Fig. 1. Hypothetical form of portion of mature frond, 

 based on transxerse sections shown in Figs. 2 and 4. From the sec- 

 tions of the yoimg fronds we learn that the frond was once pinnate and 

 the bundle system strongly dichotomous. Further, while the exact 

 form is somewhat conjectural the successive increase or decrease in the 

 width of the several pinnules, as cut transversely, pei-mits a nearly correct 

 interpretation. (See Fig. 5, showing the best known related form.) 



PI. LXII, Fig. 2. Transverse section of a very young frond embedded 

 in ramentum, only partly shown. The position of the petiole is shown 

 in dotted line. The closely folded pinnules show a series of ridges cor- 

 responding to the venation and bundle system, the bimdles being indi- 

 cated in the drawing l)y small circles. The ridges are probably due to 

 some condition attendant upon silicification. X 25. (See PI. LXIII, 

 Fig. 1.) 



PL LXII, Fig. 3. Camera lucida drawing of transverse section of 

 the ramental chaff or flattened hairs enveloping the still folded young 

 fronds shown in PL LXII, Fig. 2, and PL LXIII, Fig. 1. These hairs 

 were several inches in length and a single cell in thickness at their origin. 

 Well out toward their tips they are three and four cells in thickness, as 

 here shown. X 65. 



PL LXIII, Fig. 1. Transverse section of an emerging young frond 

 1 cm. distant from that shown in PL LXII, Fig. 2, but larger and lietter 

 preserved. The pinnules with their bundles indicated are folded l:)ack 

 to face, in two ranks, this indicating a once pinnate frond with the pre- 

 foliation of Cycadeoidea (see Wieland, loc. cit.) and the living Dion. 

 The somewhat furrowed (or dried?) rachis is seen at the lower right- 

 hand corner, the interior stippled area marking the fern-like bundle 

 system. The arrow points toward the central axis of the trimk, the 

 rachis being distal. X 25. 



« Professor Fontaine's figures of these forms maybe consulted. They are respectively given on pl.l.xiv, 

 figs. 1 and 2, and pi. xlii, fig. 1, of the first paper on the Mesozoic Floras of the United States, Twentietli 

 Ann. Rep. U. S. Geol. Survey, Pt. II, 1900. 



