120 D. WHITE — A NEW T.ENTOPTEKOID FERN AND ITS ALLIES. 



slightly distant, at right angles or reflexed below, becoming more oblique 

 above, ribbon-like, gradually tapering from the lower part, with borders 

 straight or slightly undulate and nearly parallel, to a rather acute ti]>, 

 long, sometimes reaching a length of 8 cm or more, and measuring 6 to 

 13 mm in width, the lower ones slightly narrowed toward the cordate, 

 nearly symmetrical base with its narrowed attachment which overlaps 

 the marginal lamina of the rachis, the higher ones becoming attached by 

 the whole base, those near the top of the pinnae becoming shorter, more 

 distinctly decurrent and confluent, the margins more rapidly converging ; 

 limb of the pinnules rather thick, dull, broadly canaliculate along the 

 midrib, somewhat convex near the borders, overlapping the marginal 

 lamina? of the rachis. constricted to a rather narrow attachment in the 

 lower and middle pinnules, spreading and uniting those near the apex 

 of the pinna? where it forms a wing incised by acute and decurring angles 

 at the confluence of the pinnules ; nervation tamiopteroicl, midrib strong, 

 depressed, broad and striate beneath, broadly canaliculate above, origi- 

 nating from the central portion of the rachis, passing along the middle of 

 the lamina and tapering to the apex of the pinnule ; lateral nerves rather 

 fine salient above, distinct beneath, originating at an oblique or some- 

 times nearly a right angle from a slender cord-like bundle often distinctly 

 in relief traversing the center of the canal, usually forking at or near the 

 midrib, rarely simple, curving quickly if oblique, and passing fairly 

 straight and generally parallel perpendicularly to the border, usually 

 forking again at a varying distance in the lamina, and counting 24 to 28 

 per cm at the margin ; basal nervils of the upper decurrent pinnules 

 springing from the rachis ; those of the uppermost alethopteroid pin- 

 nules becoming rather more oblique in passing to the margin. 



Locality. — Represented by ten specimens from Hobbs 1 bank, nine miles 

 south of Clinton, Missouri, and one specimen from Deepwater, about 

 eight miles southeast of Clinton. 



Specific Resemblances. — Among the known Paleozoic plants are several 

 species described as Damseites, Alethopteris, Taeniopteris and Desmopteris 

 which have many characters in common with Tivnioptcris misxoiiricnsis. 

 Of the American forms, Danssites {Alethopteris) macrophylla, Newb. sp., 

 Alethopteris maxima, Andr., the types ranged under Orthogoniopteris and 

 Protoblechnum, and an unpublished species of Callipteridium described by 

 Lesquereux deserve comparison. Newberry's Alethopteris macrophylla, 1 

 the fully developed pinnules of which are somewhat similar to tbose of 

 our specimens, is alethopteroid in arrangement, only the lowest, so far as 

 I have observed, becoming contracted to the obliquely cordate base. 

 Besides its more delicate habit, it further differs by the obliquity of the 



1. Geol. suvv. Ohio, Pal. I. i>. 383, pi. xlviii, figs. ::, :■„,. 



