DESCRIPTION OF THE SPECIES. 107 



ACEOSTICHOPTERIS LONGIPENNIS, sp. nOV. 

 Plate CLXX. Fig. 10; Plato CLXXr. Figs. 1, 5, 7. 



Fronds with very long, more or less flexuous i)innae, apparently creep- 

 ing; ultimate pinna; or pinnules subopposite to alternate, going off at a 

 large angle and arching slightly away from the principal racliis, ending in 

 one or two oblong lobes which have oblong blunt teeth. At base they are 

 cut into pinnules or segments which are cuneate, fan-shaped, and these in 

 turn are cut into oblong segments, which end in oblong or ovate-subacute 

 teeth; the pinimles or segments, in ascending from the base of the ultimate 

 pinnaj towards their summits, diminish in the number of segments; nerves 

 slender but distinct, flabellately diverging and forking dichotomously, the 

 ultimate branches ending in the teeth; fructification as in the genus, and 

 occurring on the basal upper lobe in the upper part of the frond. In the 

 lower parts of the same they are found on the upper and lower basal lobes; 

 the fructified lobes rounded or elliptical, and close appressed to the prin- 

 cipal rachis. 



Localities: Abundant at Belt and Covington streets, Baltimore; most 

 common at the first-named locality. 



PI. CLXXI, Fig. 1, seems to represent a .sterile form. This conies 

 from Belt street. Figure 7 of the same plate has both of the basal lobes 

 fructified. Tliis comes from Covington street. Figure .5 of the same 

 plate has only the fructified lobes retained on the principal rachis. 



ACKOSTICHOPTERIS DENSIFOLIA, sp. nov. 

 Plato XCIV, Fig. 4; Pl.ate CLXX, Fig. 11; Pliite CLXXI, Figs. 2, 6; Pl.ite CLXXII, Fig. 13. 



Principal rachis .slender; ultimate pinn;v or pinnules densely crowded, 

 often overlajiping, very broad in proportion to their length, lower ones 

 sometimes aljiiormally short and wide as compared with those higher up, 

 being broad, fan-shaped in outline; primarv segments or i)iniiulcs dimin- 

 ishing towards the ends of tiie ultimate pinna- in the number of .segments : 

 lower pinmiles or segments cut into two or three main lobes, narrowl}- 

 oblong or ovate, ending in minute teeth; nerves as in generic description; 

 fructification on the lower basnl lol)e or on both; fructified lobes elliptical 

 in shape and proportionally very large. 



