FERNS— MEGALOPTERIDE.E—ALETHOPTERIS. 113 



irregularly striated stein nearly 10 cm. in lengtli and about 2.5 cm. in width, 

 to the upper part of which are apparently attached a well-developed pinna 

 and one, or perhaps several, smaller pinnte comparable to A. Germari or A. 

 filiciformis. But what is remarkable in the specimen is the circumstance 

 that the large fragment of rachis is somewhat densely clothed with large 

 leaflike scales. The latter are rathei- thin, not rigid, 7 to 11 mm. or more 

 in lengtli, 3 to 5 or . G mm. in width, ovate or oblong-ovate, somewhat 

 variable in form, constricted to a narrow attachment at the base, obtuse 

 at the top, inclined upward, and dorsally convex. The ventral surface of 

 these foliaceous scales is marked, when viewed with a rather strong lens, by 

 fine strise apparently consisting of rows of very small, oblong, imbricated, 

 scalelike cells, but no distinct traces of nervation are seen. This striation 

 is more distinct in the scales than in the larger lamina of the ApMebia. The 

 attachment of the scales is not clear. It is perhaps crescentic, or possibly 

 even oval. No evidence of either a fleshy composition or a flaccid nature is 

 apparent. 



The specimen seems, on the whole, to represent a segment of a large 

 rachis, perhaps belonging to one of the scabrous Pecopterids, which is rather 

 closely covered with very large, ovate or oval, semi-membranaceous scales, 

 among which several pinnae of ApMebia seem to have their attachment. 



The nature of these large scales may be the same as that of the chaff"y 

 scales seen in the segment of a smaller rachis on the same slab, just above 

 the specimen described. The smaller rachis is like that seen in direct con- 

 nection with the pinnae of Pecopteris Jenneyi. 



Locality. — Pitcher's coal bank, U. S. Nat. Mus., 5727, ()041. 



MECtALOPTERIDEvE. 



Alethopteris Sternberg, 1S26. 



Versuch, vol. i, teut., p. xxi. 



Alethopteris ambigua Lx. 



PL XXXVII, Figs. 3, 4; PI. XLI, Fig 9. 



1879. Alethopteris ambigua Lesquereux, Coal Flora, Atlas, p. 6, pi. xxxi, figs. 1. la, 

 (nou 2, 3); text, vol. i (1880), p. 182. 



Fronds tripinnate; primary pinnse rather delicate, lanceolate, acute; 

 rachis rather slender, distinctly striate, slightly flexuous; secondary pinnse 



MON XXXVII 8 



