1894.] of fossil plants, with a list of type specimens. 197 



Pecopteris exilis Phill. [= Klukia exilis (Phill).]. 



Quart. Journ. Geol. Soc, Vol. vii. 1851, p. 188, PL xiii. fig. 5. 



In 1829 Phillips^ described this species of fern from the 

 Upper Sandstones and Shales of the Yorkshire coast ; his figure 

 shows two fertile pinnae which afford but a poor idea of the actual 

 plant. The pinnules are described as " marked with round 

 swellings over the seed vessels." 



Bunbury gives a figure of a single sterile pinnule, and another 

 showing sporangia on the under surface of a fertile segment ; he 

 describes the sporangia as not in sori, but singly in regular rows 

 on each side of the midrib. He speaks of the sporangia as large 

 in proportion to the size of the leaflet, of an ovate and spherical 

 form, with regular striae radiating from a central point ; they are 

 compared with those of Schizacece, and especially with the spo- 

 rangia of Anemia and Mohria. Among fossil forms Senftenbergia 

 presents the closest resemblance, but its sporangia differ in having 

 apical rings of two layers instead of one. 



Solms-Laubach^, in referring to Senftenbergia and Bunbury's 

 description of the fertile specimen of Pecopteris exilis, suggests 

 the desirability of a re-examination of the latter. More recently 

 Raciborski'^ has made an exceedingly important contribution to 

 our botanical knowledge of Mesozoic ferns. He describes several 

 specimens of fertile fern fronds from Jurassic strata in the neigh- 

 bourhood of Cracow, and Pecopteris exilis is discussed at some 

 length as a Jurassic representative of the Schizacece. 



E,aciborski points out that Bunbury was the first to give any 

 accurate account of the sporangia of Phillips' species ; but ap- 

 parently Schimper and some other palasobotanists have overlooked 

 Bunbury's paper. 



Several fertile segments of this species have been found in 

 the Cracow beds*, and an examination of the sporangia enables 

 Raciborski to confirm the description of the English specimen, 

 as well as its inclusion in the family Schizacece. As our know- 

 ledge of the fructification of fossil ferns gradually increases, we 

 are able to dispense with such provisional generic terms as Peco- 

 pteris, Sphenopteris, &c., and are in a position to institute new 

 names expressive of some definite botanical affinity. 



In the case of Pecopteris exilis Raciborski has proposed a 

 new genus Klukia, to be included with Anemia and others in 

 the Schizacece. The introduction of a new term is usually to 

 be avoided, especially in a subject like fossil botany, which is 

 hopelessly overloaded with synonym lists ; but in cases where 



1 lUust. Geol. Yorks. 1829, PL viii. fig. 16. 



2 Fossil Botany, p. 152. 



3 Bot. Jahrb. (Engler) Vol. xiii. 1890, p. 1. 



4 Ibid. PL i. figs. 17—19. 



