92 I:L0RA of lower coal measures of MISSOURI. 



very long linear-triang-ular Avlien large, tapering nearly the whole length, 

 the sides conA-erging rather more rapidh' in approaching the i-ather slender 

 tip; nltimate rachis slightly terete beneath, sulcate on the ventral surface, 

 rather slender, rigid, or slightly curved; pinnules alternate, close, usually 

 nearly touching, sometimes a little distant, open, the lower ones nearh' at 

 a right angle to the rachis, decurrent; when young, oval, curving outward, 

 and connected halfway up, becoming oblong or oblong-ovate, narrowing 

 slightly from the base up toward the obtusely rounded tip, separated to 

 near the rachis b}' a very narrow decurrent sinus that cuts to near the mid- 

 rib on the upper side of the largest pinnules; lamina of moderate thickness, 

 depressed over the midrib, arched slightly backward at the margins, nar- 

 roNAdy decurrent from the bases of the pinnules, either rather densely covered 

 with short scales or scaly hairs lying parallel to the nervation, or, when 

 macerated, appearing broAvnish or transparent, the scaly covering- usually 

 remainmg, however, in portions of the specimen; nervation clear on the 

 dorsal surface of the pinnule, or more or less distinct in the macerated 

 specimens; midrib rather slender, more or less decurrent, and tapering to 

 near the apex of the larger pinnules; lateral nerves fine, originating at a 

 rather wide angle and either, in the smallest pinnules, turning upward, 

 simple, or, in the larger pinnules, forking near the base, and passing, with 

 slight curvature, quite obliquely to the mai-gin, the upper branch forking 

 again in the largest simple pinnules; fructification in small sori situated a 

 little distant in a row a little within the margin of the pinnules or lobes; 

 sporangia 4 to 6 in the sori, small, lanceolate, acute at the upper end, 

 attached at or near the larger rounded lower end. 



Pecopteris vestita Lx., which was originally described from the vicinity 

 of Clinton, Missouri, is represented among the collections in hand by a fine 

 series of typical specimens. The species is in general fairly well marked 

 by the long, tapering, slender pinnae, the pinnules broadest near the base 

 and decurrent, the upper surface densely covered by short scalelike hairs 

 or very minute chaffy scales arranged parallel to the nerves, which they 

 g-enerally obscure, and the slender oblique nervation. 



The fossil shown in PI. XXXIII, Fig. 2, jiresumably a secondary pinna, 

 corresponds in size and in details to one of the lateral pinnae aiTanged 

 alternateh^ along a slightly flexuous rachis, about 6 mm. in diameter, on 

 one of the larger slabs. The pinnse in Fig. 5, especially in the upper part, 



