396 STUDIES IN FOSSIL BOTANY 



the structure was described by Williamson, agrees so 

 closely with L. Lomaxi that it must clearly have 

 belonged to some plant of the Lyginodendron type. 

 Physostoma elegans 1 ( = Lageno stoma physoides), another 

 of Williamson's discoveries, is more remarkable, and 

 perhaps more primitive, for here the micropylar tube is 

 replaced by a ring of about ten free tentacles, surrounding 

 the apex of the nucellus, and apparently corresponding 

 to the loculi of the canopy in Lagenostoma. In neither 

 of the seeds last mentioned has a cupule as yet been 

 discovered. 



6. The Microsporangia. — Nothing certain was known 

 of the male fructification of Lyginodendron, or indeed of 

 that of any Pteridosperm, until Mr. Kidston, in 1 905, dis- 

 covered a species of Crossotheca {C.Honinghausi, Kidston) 

 in organic connection with the foliage of Lyginodendron? 

 The genus Crossotheca was founded by Zeiller in 1883, 3 

 on a fructification found by him in connection with a 

 Sphenopteris (see Fig. 109, F, Vol. I. p. 280); the 

 genus was characterised by the arrangement of the 

 sporangia, hanging from the lower surface of the oval 

 or spathulate fertile segments, the whole resembling an 

 epaulet with its fringe. On account of the absence of 

 an annulus and the appearance of a slight fusion 

 between the sporangia, Zeiller referred Crossotheca to 



1 A full investigation of this seed by Professor 1"\ W. Oliver has 

 appeared in the Annals of Botany for January 1909. 



2 Kidston, " On the Occurrence of Microsporangia in Organic Connection 

 with the Foliage of Lyginodendron," Proc. Roy. Soc. (B) vol. lxxvi. p. 358, 

 1905; "On the Microsporangia of the Pteridospermeae," Phil. Trans. 

 Roy. Soc. B, vol. 198, 1906. 



3 " Fructifications de Fougeres du Terrain Houiller," Ann. sci. not. Bot. 

 ser. vi. t. xvi. 



