X] NOMENCLATURE. 379 



the stems and the fertile shoots of the Asterophyllites type^ 

 which he describes. Another member of the Eiwalamites group, 

 which is better known as regards its foliage-shoots, is Oalamites 

 ramosus, a species first described by Artis' in 1825. Stems of 

 this species have been found in connection with the branches 

 and leaves of the Annularia' type, bearing Calamostachys" cones. 

 In all probability pith-casts included in the sub-genus Eucala- 

 mites belonged to stems with foliage-shoots and probably also 

 with cones of more than one form. 



In the above account of a few common pith-casts it has 

 been pointed out that there is occasionally satisfactory evidence 

 for connecting certain casts with wood of a particular structure, 

 and with sterile and fertile foliage-shoots of a definite type. It 

 is, however, impossible in many cases to recognise with any 

 certainty the leaf-bearing branches and strobili of the different 

 casts of Oalamites ; it is equally impossible to determine what 

 type of pith-cast or what type of foliage-shoots belongs to 

 petrified stem-fragments in which it is possible to investigate 

 the microscopical features. The scattered and piece-meal 

 nature of the material on which our general knowledge of 

 Calamitean plants is based, necessitates a system of nomen- 

 clature which is artificial and clumsy; but the apparent 

 absurdity of attaching different names to fragments, which we 

 believe to be portions of the same genus, is of convenience 

 from the point of view of the geologist and the systematist. 

 As our material increases it will be possible to further simplify 

 the nomenclature for Calamarian plants, but it is unwise to 

 allow our desire for a simpler terminology to lead us into 

 proposals which are based rather on suppositions than on 

 established fact. If it were possible to discriminate between 

 pith-casts of stems having the different anatomical characters 

 designated by the three sub-genera, Arthropitys, Arthrodendron 

 and Calamodendron, the genus Oalamites might be used in a 

 much narrower and probably more natural sense than that 

 which we have adopted. The tests made use of by some 



> Stur (87), PI. X. 2 Artis (25), PI. ii. » Weiss, loc. cit. Pis. v. vi. and x. 



