Affinities of Fossil Plants from the Palaeozoic Bocks. 167 



Lepidostrobus. They are of tetrahedral form, becoming spheroidal 

 when mature, and each spore has a hollow, annular wing running 

 round its equator. The wing is no doubt formed by a dilation of the 

 cuticle,* and not, as Williamson supposed, from the abortive sister- 

 cells. 



Spencerites majusculus, the new species, is much larger than the 

 former, the axis of the cone being twice as thick. The anatomy is 

 similar, but the sporophylls, and consequently the leaf-traces, are 

 more numerous. The sporophylls, which are arranged in alter- 

 nating verticils, are relatively short, and of peculiar form ; the lamina 

 is very thick, and of great tangential width. The sporangia are like 

 those of the former species, and similarly inserted, but the spores 

 are quite different. They are smaller than those of S. insignis, and 

 have the form of quadrants of a sphere, with narrow wings along 

 their three angles. 



The genus is separated from Lepidostrobus, mainly on account of 

 the very different mode of insertion of the sporangia, a character 

 which is accompanied by differences in the form of the sporophylls 

 and sporangia, the structure of the sporangial wall and of the spores, 

 and the whole habit of the strobilus. 



Spencerites, and especially S. insignis, bears a considerable re- 

 semblance to the Sigillariostrobus Crepini, of Zeiller, but cannot be 

 united with the genus Sigillariostrobus, for the insertion of the 

 sporangia in the latter, as shown in the Sigillariostrobus ciliaius of 

 Kidston, is totally different. The author is much indebted both to 

 M. Zeiller and Mr. Kidston, for the loan of their specimens for 

 examination. 



The generic and specific characters may provisionally run as 

 follows : — 



Spencerites, gen. nov. 



Cone consisting of a cylindrical axis, bearing numerous simple 

 sporophylls, arranged spirally, or in crowded alternating verticils. 



Sporophylls short, formed of a sub-cylindrical pedicel, expanding 

 into a large peltate lamina. 



Sporangia solitary on each sporophyll, inserted, by a narrow base, 

 on the upper surface of the lamina, but free from the pedicel. 



Sporangial wall consisting of a single layer of prosenchymatous 

 cells. Spores winged. 



1. Spencerites insignis, (Will). 



Lepidostrobus, sp., Will. " Organization of the Fossil Plants of 

 the Coal-measures," Part 9, ' Phil. Trans.,' 1878, p. 340, figs. 39 to 

 47 and 52 to 57. 



* Cf. Solms-Laubach, ' Fossil Botany,' p. 239. 



