Fructification of two Coal-measure Ferns, 23 



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 exan- 

 nulate sporangia are regarded by Stur as portions of an inda- 

 sium which has burst at maturity 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 Galymmatotheca ; but in the latter genus the sporangia are 

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

 they so fully united to each other. In Galymmatotheca 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 pinnas are only borne at 

 the base of the frond. 



Crossotheca Jimhriata, KIdston, n. s. 

 (PI. I. figs. 1-8.) 



Descri])tion. — Frond tripinnate, pinnaa deltoid, subalternate. 

 Fertile and barren pinna 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. 



RemarJcs. — The specimens of Crossotheca fcmhriata which I 

 have the pleasure of describing were communicated to me by 

 Mr. William Hemingway, to whom my thanks ai-e 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 

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

 of a rachis, to which probably the fruiting pinna was attached. 



The sporangia are borne as a fringe at the margin of what 

 appears to have been an oval disk. This disk and, more 

 particularly, the sporangia appear to have possessed a con- 

 siderable thickness of tissue, which contrasts markedly with 

 the delicate structure of the barren pinnules. The sporangia 

 are converted into a bright, brittle, carbonaceous substance, 

 so that in splitting the stone in almost all cases they are more 

 or less fractured ; and, further, in no case where they are at 

 all well preserved have I been able to discover a complete 



