674 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



EQLISETACEiE. 



EqUISETUM HAGUEI 11. sp. 

 PI. LXXXI, fig.s. 3, 4. 



Stem simple, striate, articulate; articulations rather long; sheaths 

 short; teeth long, appressed, sharp-pointed. 



This species is represented Idv numerous fragments, many of which, 

 however, show the sheaths. The stem is from 4 to 6 mm. liroad and the 

 articulations are 5 to G cm. in length. It is jilainly striate, with usually 9 

 ribs. The sheaths, which are darker in color than the stem, are 6 or 7 mm. 

 in length and are provided with closely appressed, very sharp-pointed teeth, 

 about 3 mm. long. 



If there are 8 or 9 riljs now visible in the flattened stems, it seems 

 safe to assume, inasmuch as they were cjdindrical, tliat they have 16 or 18 

 ribs, and an equal number of teeth. 



It was at first supposed that these specimens could be referred to E. 

 limosnm L, [see following species],^ as identihed by Lesquereux from mate- 

 rial collected by Hayden from basaltic rocks near the Yellowstone I^ake ; 

 but an examination of the type specimen preserved in the United States 

 National Museum (No. 41) shows that they can not be the same. Lesque- 

 reux's specimen has only 4 or 5 ribs visible, making, as he says, about 10 

 for the entire diameter, while this has 16 to 18, and possibly as many as 20. 

 The segments of the stem are only about 1 cm. in length in Lesquereux's 

 specimen and 6 or 7 cm. in the one under discussion. The sheaths are 

 also longer and the teeth sharper in E. Jiaguei. 



Among living species this seems to approach closely to E. limosum L.; 

 more closely, in fact, than does the specimen referred to E. limosum bj' 

 Lesquereux. 



I have named this species in hdiior of Mv. Arnold Hague, who pointed 

 out the locality where it was found. 



Habitat: Southeastern end of hill north of Lost Creek, Yellowstone 

 National Park, bed No. 5; collected by F. H. Knowltou, 1888. 



'Fifth Aun. Kept. U. S. Geol. aii(l(ieog. Surv. Terr.. 1871 (1872), p. 299; Tert. Fl., p. 69, PI. VI, tig. 5. 



