298 MESOZOIC FLORAS OF UNITED STATES. 



lowest ones in the basal rounded lolies are several times forked and tend to 

 form flabellate Inmdles, wiiicli fill the lobes. 



There is hardly a doubt that this is a species of Cladophlebis distinct 

 from the other species of this genus found in the (ievser beds, and so far as 

 w(> can judge from so small an amount of matei'ial, it is most probably 

 identical with C. coiistridn of the Mrginia Lower Potomac. 



PI. LXXI, Fig. 26, gives a rej)resentation of this form. 



Order EQUISETALES. 



Family EQUISETACE.E. 



Genus EQUISETUM Linnteus. 



Equisetum Piiillipsii (Diinker) Brongniart. 



Pi. LXXII, Figs. 1-11. 



1S43. Equisetifes PMllipsii Dunk.: Piojrniinin. d. hohereii Gewerbschulo in Cassol, 



1843-44, p. 5. 

 1846. Equisetites PhilUpsii Dunk.: Monogr. d. Norddeutsch. Wealdenbildung. \>. 2, 



pi. i, fig. 2. 

 1849. Equisetum PhilUpsii (Dunk.) Brongn. : Tableau, p. 107. 

 1869. Equisetum PhilUpsii (Dunk.) Brongn. Schimper: Pal. Veg., Vol. I, p. 265. 

 1898. Equisetum montanense Font, in ^Veed & Pirsson: Eighteenth Ann. Pep. U. S. 



Geol. Surv., 1896-97, Pt. Ill, p. 481. (PL LXXII, Fig. 11.) 



The stems of this Equisetum, when of full size, range in diameter 

 from about 15 mm. to 2 cm. Only stems Avithout branches were seen. 

 The dimensions of the sheaths and teeth vary with the size of the stems. 

 Regarding the sheath, as indicated by the striae, it is, in the larger speci- 

 mens, from 15 mm. to 2 cm. long. The internodes in the same average 

 about 3 cm. in length. The teeth in the lai'ger specimens average about 

 6 mm. in length and are 1 mm. wide at base, their widest portion. In form 

 the teeth are narrow lancet-shaped, gradually narrowing from their bases 

 to their tips, where they are acute. Near their margins the teeth are 

 thickened, so that they appear almost as if furnished with lateral keels. 

 The portions of the teeth between these margins are depressed. At their 

 bases on the nodes the teeth are closely coherent with the stem, and each 

 one is separated from its neighbors by a sharply defined furrow, which is 

 widest at the bases of the teeth and nai'rows down the stem to a mere 



