Oil the Fructification of tivo Coal-measure Ferns. 511 



in tlie direction of their axis. The sporangia are placed 

 close together, and it is difficult to determine whether they 

 are free or united to each other. According to Zeiller they 

 appear to be united in pairs or perhaps in fours at the 

 extremities of veins which are given off from a swelling of 

 the pedicel that terminates in a thickening in the centre of 

 the fertile pinnule. 



It should be mentioned that what are here treated as 

 exannulate sporangia are regarded by Stur as portions of an 

 indusium which has burst at muturity into valves. This 

 view, however, appears to be entirely at variance with the 

 structure of the organs under consideration. 



Among fossil genera Crossotheca approaches most closely 

 to Calymmatotheca ; but in the latter genus the sporangia 

 are not attached around the margin of a prominent disc, nor 

 are they so fully united to each other. In CalynimMothcca 

 the branches bearing them are also entirely deprived of 

 foliage- pinnules, and ramify by a series of dichotomies ; and, 

 as far as observation has shown, the fruiting pinnae are only 

 borne at the base of the frond. 



Crossotheca fimhriata^ Kidston, n. s. 

 (PL XXL, Figs. 1-8.) 



Descriptio7i. — Frond tripinnate, pinnse deltoid, subalternate. 

 Fertile and barren pinnae dissimilar. Fertile pinnules simple, 

 with the limb much modified ; sporangia exannulate, linear, 

 numerous, united to each other and suspended from a central 

 disk, which is borne at the summit of a slender pedicel. 

 Barren pinnules divided into from two to seven single- 

 veined, simple or bifid, linear segments, according to their 

 position on the pinna. 



Remarks. — The specimens of Crossotheca fimhriata which I 

 have the pleasure of describing were communicated to me by 

 Mr Walter Hemingway, to whom my thanks are due for 

 the opportunity of examining this interesting addition to the 

 Coal-measure flora of Britain. 



Figs. 1-3 show portions of what are probably primary 

 pinnse ; at the right of the pinna in fig. 1 is a small fragment 



