158 Sphenophyllum as a branch of Asterophyllites. 



equally well-defined Sphenophyllum leaves. Renault J admits 

 the practical identity of the stems, but considers that Wil- 

 liamson's specimens should be referred to Sphenophyllum 

 and not to Asterophyllites. I have had the privilege- of 

 examining the sections of Professors Williamson and 

 Renault, and have convinced myself of the good grounds on 

 which these authors respectively referred their specimens to 

 Asterophyllites and Sphenophyllum. 



That Calamites possessed branches indistinguishable 

 from Asterophyllites has been often asserted. Without, how- 

 ever, venturing to go so far as to accept it as proved that the 

 three genera, Calamites, Asterophyllites, and Sphenophyllum y 

 are in reality one, it seems reasonable, considering the 

 evidence obtained for the connection of Asterophyllites and 

 Calamites on the one hand and Asterophyllites and Spheno- 

 phyllum on the other, to regard the term Asterophyllites as 

 indicating a particular morphological condition rather than 

 a distinct genus. The definition of Sphenophyllum, as it now 

 stands, does not include leaf-forms having the Asterophylli- 

 tean characters ; if the genus be retained the definition must 

 be altered so as to include not only the wedge-shaped leaves 

 which may be entire, toothed, or more or less deeply lobed, 

 but also forms having a mid-rib and possessing Astero- 

 phyllitean characters. 



1 Cours de Botanique fossile, deuxieme annee, pp. 91 and 92 (Paris, 

 1882). 



