290 Systematic Paleontology 



obliquely and curve outwards to meet the margin, forking repeatetllv, 

 and anastomosing to form meshes that are irregular in size and shape, 

 being mostly elongate, oblong, or subrhombic."— Fontaine, 1890. 



No additional material referable to this species having been discovered, 

 its claim to validity rests upon the foregoing meagre description and the 

 rare fragments figured by Fontaine which might equally well be refer- 

 able to either of the other Potomac species. In fact such a disposition 

 would probably do no violence to the facts. 



Occurrence. — Patusent Foemation. Fi-edericksburg, Virginia. 



Collection. — U. S. National Museum. 



Family MARATTIACEAE (?) 



Genus TAENIOPTERIS Brongniart 

 [Prodrome, 1828, p. 61] 



Brongniart gives the following diagnosis of Tceniopteris in his 

 Prodrome ^ : 



Fronde simple, entiere, etroite, k bords paralleles, transversee par une 

 nervure moyenne, forte, gpaisse, qui s'etend jusqu'a I'extremete; nervures 

 secondaires presque simples ou bifurquees a la base, presque perpendiculaires 

 sur la nervure moyenne. 



The type was the Jurassic species Tceniopteris vittata; which was 

 compared with the existing genera Dancea and Angiopteris of the Marat- 

 tiacese. 



This diagnosis is repeated in Latin without material change in the 

 Histoire." In a later' work the same author institutes various com- 

 parisons with modem ferns, and points out that the genus probably 

 includes forms of diverse botanical affinities. Three groups are recog- 

 nized: (1) Those with simple fronds like Tceniopteris vittata, which 

 suggest modern forms of AcrosticJiumj (2) those with pinnate or bi- 

 ^ pinnate fronds with articulated pinnaa like T. Munsteri, which Brongni- 

 art is positive is a member of the Marattiacese, and (3) those with non- 

 articulate pinnate fronds like T. Bertrandi. 



^ Prodrome, 1828, p. 61. 



^ Brongniart Hist. vgg6t. foss., 1831, p. 262. 



* Brongniart, Tableau, 1849, p. 21. 



