o78 T. G. HALLE. [Nov. 1913. 



of this wider genus Ftilophyllnni. From the typical Zamitcs 

 it would diifer mainly by the less marked rounding of the 

 basal corners and by the smaller size. The former distinction 

 may be available in some cases but it would only be a dif- 

 ference of degree, since even the very slightly rounded base of 

 some of the Antarctic Zamites-forms belongs to the same type 

 as that of Z. gigas and other typical species. If the speci- 

 mens figured in PL lU, fig. 7, of this paper are compared 

 with those in figures 1 — () of the same plate, which show 

 typical pinna-bases of different species, from Greenland and 

 (Iraham Land, referred by the present writer to Zamitcs^ 

 it will be difficult to find any dift'erence sufficiently distinct 

 to be expressed in a diagnosis. Indeed, it is not impossible 

 that, w^ith the classification advocated by Professor Seward. 

 the specimens in PI. 10, fig. 7, might be referred by some 

 authors to Ptilopliijlliim. Yet this figure shows very typical 

 specimens of Zamites gigas: only, these are reduced to the 

 average size of the Ftiloj^hyUiim-fronds. It would appear 

 from a consideration of this figure that the more stringent 

 definition of Zamites is based to a great extent on the size. 

 A difference of size may be a character of some importance; 

 but it would not seem to be convenient to base on such a 

 distinction a separation of two form-genera of a kind of 

 fronds which show a rather great variation in size. 



The choice is thus between distinguishing Zamites and Ftilo- 

 pliyllum in accordance with either the difference of shape of the 

 pinna-base or the difference in the degree of rounding of the 

 latter and in the size of the frond. As the latter course 

 would involve both a mixing of two types with a diff'erent 

 symmetry of the pinna-bases in one genus and a vaguer gene- 

 ric distinction between the genera, it does not appear to pre- 

 sent any advantages. 



It remains to discuss the question of the classification of 

 sterile Coniferous shoots. I have created a new name, Elato- 

 cladus, to be used for such sterile shoots of Conifers, whether 



