8 PEOCEEDINGS OF THE NATION" AL MUSEUM vol.72 



it is somewhat rounded in the second specimen figured. It is pro- 

 duced into a short and stout recurved style. There is a more or well- 

 developed sinus at the base resulting in a blunt point on the ventral 

 side and a more prominent and sharper point on the dorsal side. 

 The dorsal margin or keel is smooth and nearly semicircular in 

 profile. The endocarp or seed was obviously crustaceous, since it 

 usually stands out sharply and distinctly from the collapsed exocarp. 

 It is pronouncedly campylotropous, the radicular end, twice the 

 diameter of the much curved distal end lying close to the basal sinus 

 and toward the dorsal margin. In the second, and what is believed 

 to be the more typical, form figured a portion of the resistant seed 

 coat offset and reversed along the upper dorsal margin. 



These fruits are much like those of a large number of existing 

 species of Potamogeton without being significantly like any particu- 

 lar one. 



The genus contains about 70 widely distributed existing species 

 of temperate regions. It is not infrequent in the geological record, 

 although few fossil species are as well preserved as the present one. 

 Upwards of 50 fossil species have been described ranging in age 

 from the Upper Cretaceous to the Pleistocene, and the genus is very 

 well represented by still existing species at the latter horizon. A 

 characteristic species, Potatmogeton ripleyensis Berry ,^ from the Rip- 

 ley Upper Cretaceous of western Tennessee is quite similar in its 

 foliage to the present Esmeralda form. 



Occurrence. — Coal prospect 4 miles southeast of Morgan Ranch 

 and 15 miles west of Hawthorne, Mineral County, Nev. 



C oty pes.— Cdit. No. 37301, U.S.N.M. 



Order SALICALES 



Family SALICACEAE 



Genus SALIX Linnaeus 



SALIX INQUIRENDA Knowlton (?) 



Salix inquirenda Knowlton, U. S. Geol. Surv. Prof. Paper 140, p. 32, pi. 11, 



figs. 1, 2, 1926. 

 f^alix angusta Al Braun, Knowlton, U. S. Geol. Surv. 21st Ann. Kept., 



pt. 2, p. 212, pi. 30, fig. 22, 1901. 



Knowlton referred a fragment of a small willow leaf from the 

 Esmeralda formation to /Salix angusta Al. Braun — a European Ter- 

 tiary form. The fact that it has been recorded from as various 

 western American horizons as the Mesaverde, Lance, Green River, 



" Berry, Edward W., The flora of the Ripley formation : U. S. Geol. Surv. Prof. Paper 

 136, p. 34, pi. 3, fig. 5 ; pi. 23, figs. 1-3, 1925, 



