45 



Fucoid. It may be, however, a kind of sponge, as it resembles some tubulose 

 species of this class by its punctate or perforated-like surface, an appearance 

 which, as remarked above, may be due to the porous compound of the matrix. 

 Habitat. — Niobrara group of the Cretaceous, about 100 feet above the 

 top of the Dakota group, six miles north of Fort Harker ; on the highest point 

 of the divide between Saline Fork and Smoky Hill River. It is there mixed 

 with a prodigious quantity of fossil shells. It is the only species described 

 in this paper from out of the Dakota group. In Europe it has been recog- 

 nized in the Dyas or Permian. 



Filices. 

 Lygodidm trichomanoides, sp. nov., PI. i, Fig. 2. 



Pinna linear from the tnincate base to the middle, enlarged and lobed upwards from the forking of 

 the medial nerve ; veins broadly oblique, distinct, simple or branching from the base. 



Lygodlum (?) species, Lesqx., American Journal of Science and Arts, vol. 



xlvi, p. 91. 



This fragment of a fern, too small for exact determination, was doubt- 

 fully referred at first to a Lygodium, though I do not know of any species of 

 this genus to which it may be related. Of all the ferns which I have been 

 able to compare, none appears to have any marked analogy with it but 

 Trichomanes pirmatum, Schwartz, and this only by the characters of its lowest 

 pinnae. The frond of this species, which inhabits the northern tropical re- 

 gions from Mexico to Brazil, is lanceolate in outline, simply pinnate, with 

 linear pinnae in the fertile state and oval lanceolate ones in the sterile fronds. 

 In these, the lowest leaflet is often enlarged and lobed from the middle up- 

 ward, by the forking of the medial nerve, exactly as in the fossil fragment. 

 The analogy is rendered more marked by the disposition of the veins, which 

 in the living species are fine, very close, distinct, simple, or branching, going 

 out in an open angle from the thick costa, with exactly the same degree of 

 divergence as seen in the fossil species. The fossil fragment, however, is 

 of a coriaceous texture, while Trichomanes species are more generally thin 

 and membranaceous. The degree of relation cannot, therefore, be positively 

 ascertained without better specimens. 



Habitat. — Fort Harker, Kansas, Leconte. 



Hymenophyllum cretaceum, Lesqx., PI. i, Figs. 3 and 4 ; PI. xxix, Fig. G. 



Frond membranaceous or subcoriaceous ; pinna? linear oblong, pinnately divided into oblanceolate 

 or cuneiform alternate oblique pinnules, declining to the convex slightly winged rachis, more or less 

 deeply bi-trilobate ; lobes obtuse, simple nerved. 



