LYOOPODIALES— LEPIDODEIfDRB.E— LEPIDODENDKON. 193 



Trunks of moderate size; bi-auches somewhat rigid, forking rather 

 infrequently; leaves slender, erect at the point of attachment, curved out- 

 ward near the base, very open, straight or turned slightly upward toward 

 the tips, narrow, tapering gradually to the very slender point; bolsters 

 rhoiiiboidal or rhomboidal-oval, acuminate at the ends, nearly symmetrical, 

 the lower portion from the leaf downward consisting of a diamond-shaped or 

 rhomboidal-clypeate surface, the upper borders nearly straight, the lateral 

 angles usually well marked, the lower margins generally very slightl}- con- 

 cave, the longer axis traversed throughout by a low, narrow keel, high at 

 the upper end where it joins the midrib, very distinct throughout, and rising 

 slightly toward its union in the somewhat protruding angle at the base of 

 the leaf; fohar cicatrices more than halfway fi-om the middle to the top 

 of the bolster, extremely narrow vertically, angular, small, apparently nar- 

 rowly triangular in the vertical sense, and usually obscure; respiratory 

 apj^endages close to the midrib, oblong, and usually obscure. 



Among the collections in hand there is but a single good frag-ment of 

 this rare species, which is hardly known from any other localit}^ in the 

 United States. The specimen, PL LIII, Fig. 2, from Dr. Britts's collection 

 agrees in all its details with others identified by Professor Lesquereux in 

 the Lacoe collection, differing only in the better preservation of its bolsters. 

 The latter, as is shown in Fig. 2a, are of the type more familiar in Lejndo- 

 dendron Sternbergii or L. li/cojMdioides. The general form of the bolsters is 

 rhombic, acute, and nearly bilaterally symmetrical. The conspicuous fea- 

 ture is, however, the diamond-shaped, slightly raised dorsal shield, which 

 stands slightly in relief, especially at the slightly outward-curved ujoper end. 

 As a whole the aspect of the shield is suggestive of L. opMurus, although 

 the lateral angles are more pronounced than in that species, while the nearly 

 straight upper margins converge to an acute point which seems to invest the 

 lower boundary of the narrow leaf scar. In most cases the apex of this 

 shield is broken, and the effect is a somewhat irreg'ular, usually concave 

 fi'acture, like that seen in fig'. 5 on pi. Ixiii of the Coal Flora. Where pre- 

 served, however, it usually shows little evidence of a leaf scar except a very 

 small deltoid area of broken carbonaceous matter at the upper end of the 

 keel, with short lateral lines which are continuous with the upper margins 

 of the shield. Fig. 5a, in the above-mentioned plate, shows the scar extend- 

 ing downward, erroneously in my judgment. The midrib of the leaf, 

 MON xxxvii 13 



