656 GEOLOGY' OF THE yello\vsto>;e national pahk. 



(")XOCLEA MINIMA IL. Sj) 



ri. LXXVII, tigs. 11-LJ. 



Fertile frond nnkiiDwu; sterile frond small, apparently deltoid in 

 outline, deeply pinnatifld into short, rounded, obtuse pinna-, whieli are 

 ]ierfectlv entire or are cut into few large, coarse teeth; nervation as in the 

 living 0. si'iisibil/.s. 



This tine little s|)ecies is represented l)v a dozen or more speeiineus, 

 the best of which are figured. They are all a})j)arentlv fragments, and 

 consequently it is impossible to make out the real shape of the frond with 

 any certainty. One of the most perfect specimens (fig. 13) is about 3.5 

 cm. long, and represents the upper portion of a frond or ])ossibly pinnule, 

 if it is a large compound frond The larger fragment (tig. lo) is 4.5 cm. 

 lono- and about 4 cm. broad, but it is broken at botli ends and there is no 

 means of determining how Ion;;- it was originally. Fig. 12 at first sight 

 seems to be entirely dift'erent from the others, liut on comparing it with fig. 

 14 the only difference observal)le is that one is cut into a few coarse teeth 

 and the other is entire. The nervation seems to be the same in all and to 

 be identical with tliat of the living sensitive fern. 



Regarding this interesting species, 1 am somewhat uncertain as to the 

 shape of the frond, and less so as to the genus to which it belongs. Two of 

 the most perfect forms (figs. 11, 13) seem to have come from the upper 

 portion of a frond sinfilar in general shape to the sterile frond of Oiioclca 

 sfiisihiUs; but, on the other hand, figs. 12 and 14 have much the appear- 

 ance of l)eing deeply lobed pinna?, resembling some of the lower ones in 

 (). seiisihilii. More material will be necessary to settle this point, but in 

 the meantime the species is characteristic enough to be readily distinguish- 

 able, and hence is available for geological purposes. 



This species was at first thought to be identical with a plant that has 

 been described under the MS. name of Woodivardla creiiata, which comes 

 from Point of Rocks, Wyoming. This latter is known only from a mere 

 fragment, however, and if ailditional material could be obtained it might 

 .show them to Ije the same. At present TF. ercudfa may be distinguished as 

 beino- much larger and in having undulate-crenate margins which are 

 minutely serrate. The nervation is practically the sanie in both. 



Oiiodea m'muud has some resemblance to 0. senslhUls fossUis from the 

 Fort Union group, near the mouth of the Yellowstone. It differs in being 



