o80 T. G. HALLE. [Nov. 1913. 



type to others — an example of this is the specimen of my 

 Elatocladus hefcrojthylla figured in p. ^5, text-fig. 18 h, of my 

 Mesozoic Flora of Graham Land — but a definite separation of 

 form-genera of sterile Conifers cannot be hoped for. Fagio- 

 pltyUnm is thus hardly available as a designation for the 

 larger group, and it is difficult to find any other existing 

 name for this purpose. Elatides would appear to be more 

 appropriate than Tagiopltyllum, as the former genus represents 

 a more general type with a less specialized kind of leaves, 

 but since cone-bearing specimens of the genus have been de- 

 scribed it would appear to be better to reserve the name for 

 these. If no other existing name can be found for the group 

 in question, there remains the possibility of creating a 

 new one. 



At first it seems no doubt to be the best to use two difi'er- 

 ent form-genera for the sterile shoots of, so to say, the com- 

 mon, non-specialized Coniferous habit, and I originally intend- 

 ed to accept this plan in the description of the Antarctic ma- 

 terial. In this material, however, as well as in most collect- 

 ions of any considerable number of fossil coniferous twigs, 

 there are numerous specimens regarding which it is impossible] 

 to say whether the habit is radial or dorsiventral, i. c, toJ 

 which of the two groups they should be referred. Moreover,' 

 there exist species which show both types in distinct develop- 

 ment on one and the same specimen. Such, for instance, is the 

 case with the dimorphic species described as Elatocladus hete- 

 rophylla, for which it would be difficult to find a suitable 

 place with the classification proposed by Professor Seward. 

 Naturally a classification should not be rejected because of 

 the existence of a single case of dimorphism, with types of 

 two form-genera in connection. But this kind of dimorphism 

 is not rare among the Conifers, and it is known also in other 

 fossil forms, for instance in Stachyotaxiis. In any case the 

 fact that the generic name Elatocladus 'includes forms with 

 leaves of the Taxites-iy]^^ as Avell as branches with leaves 



