320 Systematic Paleontology 



Genus ACROSTICHOPTERIS Fontaine 

 [Mon. U. S. Geol. Survey, vol. xv, 1890, p. 106] 



This genus is characterized as follows by its describer : " Fronds prob- 

 ably creeping, with very long, often flexuons rachises, which seem to 

 to have been more or less succulent; pinnge going off obliquely, long and 

 apparently slender; ultimate pinn^ or pinnules subopposite to alternate, 

 comparatively short, and cut down nearly to the rachis into more or less 

 cuneate-flabellate pinnules or primary segments. These are divided gen- 

 erally into cuneate-flabellate segments, which 'in turn are separated into 

 oblong segments, ending in oblong, or ovate-obtuse, or acute teeth; pin- 

 nules decurrent and forming a wing; nerves slender but distinct, flabel- 

 lately diverging, forking diehotomously, and ending in the teeth ; fructi- 

 fication occurring on the basal segments of the pinnules, in the upper 

 portions of the frond on the upper one alone, in the lower portions on the 

 upper and lower ones, the fructified segments close appressed to the prin- 

 cipal rachis. The fructified segments are so modified as to take the 

 form of leathery, rounded, or elliptical segments, which on the lower 

 side are covered by the naked sori, and seen from the upper side, espe- 

 cially when compressed on the clay, look like pods." The fructification 

 characters should be modified to include those of Acrostichopteris pluri- 

 partita, which appear to represent entire pinnules reduced to fertile seg- 

 ments and not merely basal lobes of otherwise sterile pinnules thus 

 transformed, as appears to be the case in Acrostichopteris longipennis. 



With all the collected material at hand it is difficult to see any con- 

 clusive evidence that the species included in this genus were creeping in 

 habit or had succulent rachises or that the the fertile segments were 

 covered with naked sori. There is some evidence as to fructification char- 

 acters, but this is most indefinite as regards details, and it may be noted 

 that what are called nut-like seeds when applied to fragments referred 

 by this author to his genus Baieropsis are described as above for frag- 

 ments which he referred to the present genus, although neither the fertile 

 nor the vegetative parts are distinguishable with certainty in these two 

 supposed genera. 



