[PENH allow] notes on tertiary PLANTS 89 



From this, therefore, it is clear that Taxodiiim distichum occurs 

 in the Porcupine Creek and Great Valley Groups, and it is in a high 

 degree probable that the wood and leaves belong to the same plant. 



But in view of the element of doubt which still attaches to the 

 wood on account of its state of preservation, it is necess^ary to examine 

 additional evidence bearing upon Glyptostropus and Podocarpus, and 

 to ascertain if a process of elimination will strengthen or diminish the 

 force of the arguments in favour of Taxodium. 



Schimper's diagnosis of the foliage of fossil Glyptostrobi gives 

 " Folia spiraliter disposita, sparsa, lineari-subulata," while, for the 

 most commonly known specific form (G. europseus) it reads " Foliis 

 squamiformis, adpressis, basi decurrentibus, in ramulis nonnuUibus 

 vero linearibus patentibus distichis," from which it will readily be 

 seen that the essential distinction between Taxodium and Glyptostro- 

 bus rests entirely upon the form and character of the leaf base which 

 is narrowed and very short petiolate in the one case, and decurrent in 

 the other, and it is just this difference which is represented in the 

 various diagnoses of fossil species. While the genus is widely repre- 

 sented in Cretaceous and Tertiary rocks, especially by the well-known. 

 G. europseus, it has never enlarged beyond very narrow limits, and 

 at the present time it is represented by only two living species (G. 

 heterophyllus and G. pendulus), both of which are peculiar to China. 

 In the absence of the wood of these trees, we are forced to rely upon 

 the foliage of the fossil species which, though abundant in the same 

 deposits, affords no conclusive evidence as to its connection with the 

 wood now under discussion. 



As already pointed out, Glyptostrobus horsfieldii has been trans- 

 ferred to Podocarpus where it falls in the section Dacrj-ocarpus as the 

 •most nearly allied to Taxodium. As exhibited in P. dacrydioides,^ the 

 foliage presents a striking similarity to that of fossil species of Glyptos- 

 trobus, is shown by the decurrent base and by the more general features 

 'given in commonly accepted diagnoses : — " Folia dif ormia, alia praeser- 

 tim ramulorum fertilium parva, squamiformia, conferta, saepinsque ap- 

 pressa, >alia, ramulorum sterilium, distiche patentia, anguste, linearia 

 V. fere subulata." A careful examination of typical specimens of 

 Glyptostrobus in the collections of the Peter Eedpath Museum abun- 

 dantly confirms the resemblance thus indicated, whence it becomes 

 necessary to submit the wood to a detailed comparison with that of 

 the fossil. The wood selected for this purpose is that of Podocarpus 

 machrophylla, Don., from Japan. The diagnosis is as follows: — 



Transverse.— Growth rings narrow, becoming very broad towards the centre 

 of tlie tree. Spring wood composing "/,„ of the growth ring ; 



^ Engler & Prantl, Pflanzenfamilien. 



