64 



THE ARCHAEOPTERIS FLORA 



[CH. 



moment it may be regained as a distinct type in a position close 

 to Sphenopteridium. 



Sphenopteris, Brongniart, 1822. This well-known but well- 

 nigh indefinable type of compound frond with rounded pinnules, 

 more or less deeply lobed and contracted at the base, appears to 

 be rarer in Devonian rocks than Sphenopteridium. It, however, 

 occurs in England, Ireland, Belgium and several other regions 

 in Upper Devonian rocks. 



Distribution. From Upper Devonian onwards. 



LYCOPSIDA. 



Bothrodendron, L. et H., 1885 

 (Fig. 37). This well-known genus is 

 of frequent occurrence in Devonian 

 rocks. There has been some ten- 

 dency to include the Devonian species 

 in a distinct genus Cyclostigma 1 , as 

 originally suggested by Haughton in 

 1859. This, however, can now hardly 

 be justified 2 . There is little doubt 

 that the best known of the Devo- 

 nian species, B.KiUorkense, occurring 

 in Ireland and Bear Island, is a 

 thoroughly typical representative of 

 the genus, as the recent studies 

 of Nathorst and Johnson clearly 

 show. 



Fig. 37. Bothrodendron Kil- Practically all the organs cf B. 

 torkense, (Haugh.), from the T^-T, i rru 



Upper 6ldRefoiSouthIre- Kiltorkense are now known. The 

 land. Stern with leaf scars, lower part of the trunk consists of a 

 (Reduced nat. size.) Speci- Stigmarian rhizophore, the features 



of which agree closely with the 



men No. 20 Devonian Plant, 

 Coll., Sedgwick ' Museum, 

 Cambridge. (W. Tams photo.) Stigmanas of the Coal Measures. 



According to Johnson 3 , " the 



leaves are clearly arranged in whorls at first, but become 

 distant and quincuncially arranged in older stems, owing to 



1 This term is in any case several times preoccupied by recent Angiosperms . 



2 Johnson (1913), especially p. 505. 3 Ibid. (1913), pp. 523-4. 



