KNOWLTON] KOOTANI3 PLANTS FROM GREAT I- ALLS, MONTANA 115 



the specimens the spaces between the veins are filled with the minute 

 areolation, with little or no evidence of the slightly stronger cross- 

 veinlets. 



This species is represented at present by only two specimens, 

 neither of which, unfortunately, is sufficiently well preserved to 

 permit its complete description. So far as can be made out, these 

 leaves were approximately circular or possibly broadly reniform in 

 outline. In the larger example the length from the top of the petiole 

 to the upper margin is about 2 cm., while the greatest apparent width 

 is about 3.5 cm., but as it is very deeply heart-shaped, the general 

 outline becomes approximately circular. The same dimensions in the 

 smaller example are 1.75 cm. and about 2.5 cm., though again the 

 deeply cordate base about restores the circular outline. The very 

 thick petiole is nearly 1 cm. in length and is probably not fully pre- 

 served. The margin is not certainly preserved except for a short 

 distance on the base of the basal lobes. It is impossible to determine 

 the character of the margin on the lateral and apical portions, though 

 if not entire it could hardly have been more than strongly dentate. 



The nervation, as pointed out under the diagnosis, is very peculiar, 

 all, including the ultimate ramifications, being very deeply impressed, 

 thus showing the leaf to have been thick in texture. The primary 

 nervation is always clearly and distinctly forked, the petiole being 

 first forked at the point of entrance into the lamina, and from each 

 of these branches arise the several (6 or 8) thick branches which 

 may be observed at the base of the blade, these spreading and again 

 forking two or three times before reaching the margin, the whole 

 filling fairly evenly the area of the leaf. The character of the ulti- 

 mate nervation is well shown in the figures. 



As this is the first time the presence of Protorhipis has been noted 

 in this country, at least as such, and as the affinities and interrelation- 

 ships are still somewhat an open question, it may be worth while to 

 pass briefly in review the distribution and history of the genus. 

 Protorhipis was established by Andrae in 1853, x the type specimen 

 (P. buchii) being from the Jurassic (Lias) of Steierdorf, in Banat, 

 Hungary. It was a large leaf, some 10 or 12 cm. in width, semi- 

 orbicular in shape, with a strongly sinuate-toothed margin. The 

 base of the leaf was not preserved, but the primary nervation con- 

 sists of strong, palmately disposed forked ribs or veins, the area 

 between the veins being filled with a coarse quadrangular areolation. 



1 Fossile fl. Siebenbiirgens u. d. Banates. Abl. k. k. geol. Reichs., vol. 2, 

 abtb. 3, No. 4, 1853, p. 35, pi. vin, fig. 1. 



