108 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



Localities : It is common on both Belt and Covington streets, Balti- 

 more, and is rare at the fishing hut above Dutch Gap Canal. 



Only the sterile form, PI. XCIV, Fig. 4, was found at the last-named 

 locality. Fructified forms are tlie most common ones at Baltimore, and 

 the same is true of the preceding species, A. longipemiis. 



ACROSTICHOPTERIS PARVIFOLIA, Sp. nOV. 

 Plate XCIV, Figs. 5, 9, 10, 1-2 ; Plate CLXXI, Figs. 3, 4 ; Plate C'LXXII, Fig. 14. 



Principal rachis comparatively very stout and rigid ; ultimate pinnae 

 or pinnules short, remote, small ; pinnules or segments of tlie first order 

 cut normally into two lateral lobes and one terminal one, the latter largest, 

 minute; the principal lobes diverge flabellately, each being cut niormally 

 into two oblong lobes, which end either in very short acute triangular teeth, 

 or in oblong or ovate-obtuse to acute ones ; nerves forking dichotomously, 

 flabellately diverging, the ultimate branches ending in the teeth. 



Localities : Belt and Covington streets, Baltimore ; although rare there, 

 the most abundant species of the genus at the fishing hut above Dutch 

 Gap Canal ; rare at the entrance to Trent's Reach. 



ACROSTICHOPTERIS PARCELOBATA, .sp. UOV. 

 Plate XCIV, Figs. G, 7,11, 14. 



Ultimate pinnse or pinnules very short, terminating in a three-lobed 

 segment or pinnule; principal segments or pinnules rapidly diminishing in 

 ascending in the numljer of segments or lobes ; the lowest pinnules or 

 principal segments narrow and cuneate at base, as are all, mostly cut 

 deeply into two unequal lobes, the upper ones being the smaller, both sub- 

 divided one or more times into strap-shaped lacini?e, whicli end in nar- 

 rowly oblong obtuse teeth; nerves forking repeatedly in a dicliotomous 

 manner, so that the ultimate branches end in the teeth; fructified forms not 

 seen. 



Localities: Fishing hut above Dutch Gap Canal; road-side near Poto- 

 mac Run ; rare. 



The one shown in Fig. 11 from the Dutch Gap locality differs some- 

 what from that in Fig. 6 from the same locality and from that in Fig. 7 



