130 KLTTKIA. 



Klukia is a genus ohaxacterized by the manner of occurrence 

 and structure of the sporangia as well as by the Peeopteris or 

 Cladophlehis form of the frond ; the sporangia possess an apical 

 annulus, and occur singly on either side of the midrib of the 

 ultimate segments. 



In 1851 Bunbury' figured a fragment of a fertile pinna of 

 Peeopteris exilis, and drew attention to the agreement between 

 the fossil sporangia and those of the Schizseacese. Bunbury's 

 specimen, which is now in the Cambridge Botanical Museum, has 

 been reflgured to show more clearly the structure of the sporangia.* 

 Other figures of this species may be found in Raciborski's paper 

 already referred to, and in the Monograph of the Cracow Flora by 

 the same author. 



It is of iaterest to note that the type of sporangium characteristic 

 of the Schizseacese is met with also among Palaeozoic ferns ; the 

 well-known genus Senftenbergia of Corda' is characterized by the 

 possession of sporangia with an apical annulus consisting of two 

 rings of thick-walled cells, while the recent species have usually 

 one ring only. In, a recent publication ZeUler has shown that in 

 the sporangia of Lygodium a second ring of thick-walled cells is 

 occasionally represented ; a fact which connects more closely the 

 Palseozoic type and the recent species.* A similar example of 

 a recent Lygodium sporangium, with an indication of a double 

 annulus, was figured by Link in 1842." 



Klukia exilis (PhiU.). 



[Geol. Yorks. p. 148, pi. viii. fig. 16, 1829.] 

 (PI. XVI. Fig. 7.) 



"1829. Fecopteris exilis, PliiUips, Geol. Yorks. p. 148, pi. viii. fig. 16. 



1836. Cyathdtes obtusifoUus, Goppert, Foss. Farm. p. 328. 



1837. Peeopteris obtusifolia, Lindley & Hutton, Foss. Flor. vol. iii. pi. clviii. 



fiff. 1. 



' Bunbury (61), p. 188, pi. xiii. fig. 5. 



» Seward (94^), p. 197. 



» Corda (46), p. 91. 



* Zeiller (97*), pp. 216 and 216. Vide also Bower (99), p. 43. 



' lank (42), pi. it. fig. 2. 



