490 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



The living species to which this fossil form appears to be most 

 closely related is Woodzvardia virginica (L.) Smith, the common 

 chain-fern so v^idely distributed over eastern North America, from 

 Nova Scotia to Ontario and Michigan, and south to Florida, Louisi- 

 ana, and Arkansas. There are, however, a number of slight, though 

 apparently constant, differences. In nervation and in the size and 

 disposition of the sori, both young and mature, the two forms are 

 practically identical. The differences are as follows : In Woodzvardia 

 virginica the pinnze are almost always broadest in the middle and 

 narrowed at base, usually very markedly so ; in Woodzvardia Maxoni 

 they are always broadest at the base. In the living species the seg- 

 ments of the pinnae are rather open or spreading and have the mar- 

 gins entire, while in the fossil species the segments are very close 

 and have the ends finely serrate. In no case have auricles been 

 observed on the basal segments of the pinnae in the living species ; as 

 above stated, they are present in the fossil species. 



Among the several fossil species previously described from this 

 country, the one under discussion appears to approach closest to 

 Woodzjuardia latiloha Lesquereux^ of the Denver beds of Colorado, 

 but from this it differs essentially in size, shape, and nervation. The 

 other American fossil species, as set forth in the discussion under 

 the succeeding species, all belong to other sections of the genus as 

 gauged by the living species. 



The material upon which Woodzvardia Maxoni is based was ob- 

 tained from two localities, though practically at the same horizon. 

 The first locality is on the Brown's Park stage road about 35 miles 

 southeast of Rock Springs, Wyoming (4 miles east of Mud Springs), 

 in section 35, township 15 N., range 102 W. Collectors, C. A. Fisher 

 and T. W. Stanton, July 25, igo8. This material is mostly sterile, 

 there being only a single fragment in fruit. (See figure 3, plate lxiii.) 

 The other locality is also on the Brown's Park stage road on the 

 head of Vermilion Creek, about 47 miles southeast of Rock Springs, 

 Wyoming, in section 31. township 15 N., range loi W. Collectors, 

 A. C. Veatch and A. R. Schultz, July 27, 1908. Nearly all these 

 specimens are in fruit. (See figure i, plate Lxiv.) Both localities 

 are very near the base of the Fort Union formation, here resting 

 unconformably on the Lewis shale. 



I take pleasure in naming this species in honor of ]\Ir. William R. 

 Maxon, of the U. S. National Museum, who has rendered valued 

 assistance in the study of this and other fossil ferns. 



'Rept. U. S. Geol. Surv. Terr., vol. 7 (Tert. Fl.), 1878, p. 54, pi. iii. figs. i. r.r. 



