NO. 1862. FOSSIL FERNS FROM THE POTOMAC GROUP— BERRY. 331 



This species is not nearly so common in the Potomac as is Onycliiop- 

 sis gmi^perti, although it appears to have a wider range and be more 

 common abroad. It occurs at all horizons in the Potomac, however, 

 a vertical range which is paralleled by its range from the Valanginian 

 through the Urgonian into the Albian of Portugal. Elsewhere in 

 Europe it has been found in the Wealden of England, Belgium, and 

 Germany, the Neocomian near Quedlinburg, Saxony, and in the 

 Urgonian of Austria. Forms wdiich are identical, according to 

 Seward,^ are found in the Uintenhage series of South Africa. In 

 this country outside of the Potomac it is found in the Kootenai at 

 Great Falls, Montana, in the Shasta beds of California, and in the 

 Lakota formation of the Black Hills. 



The forms identified as this species from the supposed Jurassic 

 near Cape Lisburne, Alaska, have been shown by Knowlton to be 

 forms of Diclcsonia. Saporta in his treatment of the Portuguese 

 forms leaves them in the genus Sphenopteris but thinks that they 

 are more closely related to certain modern species of Davallia than 

 to OnycMum. His figures, however, do not bring this out with any 

 degree of certainty. Professor Seward, in discussing specimens 

 from South Africa,^ unites with this species the Japanese Jurassic 

 and Cretaceous forms designated as Thyrsopteris elongata Geyler 

 and OnycMopsis elongata Yokoyama. The reason for the proposed 

 change is the discovery in the English Wealden of more extensive 

 material which showed the psilotoides type of pinnule apically and 

 the elongata type of pinnule proximally. It is quite possible that 

 the remains from the English Wealden are all one species, but it 

 certainly does not follow that the synonymy follows such a disposi- 

 tion. The American remains identified with the elongata type show 

 that the forms with broader segments are not basal portions of 

 fronds with the distal characters of psilotoides, although there is in 

 most ferns more or less diminution in size upward. Through the 

 kindness of Professor Yokoyama the writer has received specimens 

 of 0. elongata from the Jurassic of Kaga, Japan, and these are cer- 

 tainly specifically distinct, especially in the fertile pinnee, from the 

 English forms of psilotoides. They are, therefore, included in the 

 present discussion under 0. goepperti, which is retained as a distinct 

 species. 



Occurrence. — Patuxent formation: Fredericksburg, Dutch Gap, 

 Trents Reach, near Potomac Run, Virginia; New Reservoir, Six- 

 teenth Street, District of Columbia. Arundel formation; Lang- 

 don, District of Columbia. Bay View, Maryland. Patapsco for- 

 mation: Federal HiU (Baltimore), Stump Neck, near Wellhams, 

 Maryland: Near Brooke, Hell Hole, Virginia. 



Collections. — United States National ]\Iuseum. 



1 Seward, Ann. S. Afr. Mus., vol. 4, 1903, p. 5. 



