202 MESOZOIC FLORAS OF UNITED STATES. 



forms as Podozamites lanceolatus (L. & H.) Fr. Br. from the Jurassic 

 of Oroville, California; P. lanceolatus latif alius (Fr. Br.) Heer, or 

 P. Emmonsii Newb., from the Trias of North Carolina." 



PL LXII, Figs. 1-3, PL LXIII, Fig. 1, Cycadella ramentosa Ward; 

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



PL LXII, Fig. I. Hypothetical form of portion of mature frond, 

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

 tions of the young 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, permits a nearly correct 

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



PL 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 bundles being indi- 

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

 some condition attendant upon silicification. X 25. (See PL 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 better 

 preserved. The pinnules with their bundles indicated are folded back 

 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 trunk, the 

 rachis being distal. X 25. 



3 Professor Fontaine's figures of these forms may be consulted. They are respectively given on pi. Ixiv, 

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

 Ann. Rep. U. S. Geol. Survey, Pt. 11, 1900. 



