612 PROCEEDINGS OF THE AMERICAN ACADEMY. 



however, such is not the case. That the primitive condition was for 

 the brachyblast to be subtended by a leaf trace, is further indicated 

 by the occasional presence of an axillating strand in the seedling of 

 certain living pines, — e. g. Pimis strohus, and in the mature wood of 

 certain others, — e. g. Pinus Jeffrcyi. The character of the short 

 shoot thus presents an interesting example of seedling recapitulation. 

 The leaf traces of this Pityoxylon are not confined to an axillat- 

 ing position, but are quite numerous near the pith. Their presence 

 would indicate that the leaves of this conifer were of two sorts, — 

 those borne directly on the main axis as in the seedling of living 

 pines, and those on short shoots. Such a condition has been figured 

 by Fontaine (8) in Leptostrobus, Heer. The foliar strands are jack- 

 eted by parenchyma, the whole forming a fusiform ray (Figure /). 

 Not infrequently a resin duct accompanies them in their outward 

 journey, — a condition comparable to that of the vegetative leaves of 

 some of the Abietineae, and of the sporophyll traces of some of 

 the Araucarineae (3). 



Having described the salient features in the anatomy of this speci- 

 men, it remains to consider its affinities. The presence of resin canals 

 in two planes relegates it at once to the genus Pityoxylon, Kraus, and 

 the short shoots narrow its possibilities to Larix and Pinus. There 

 are a number of reasons for excluding the former, — dentate ray 

 tracheides, thin-walled ray parenchyma, with fusion pits, abundant 

 tylosed resin canals, — none of which occur in the wood of the larch. 

 Further Larix has wood parenchyma at the end of the year's growth 

 and tangential pits, — both of which are absent here. It seems clear 

 therefore that our lignite belongs to the genus Pinus. Pines may be 

 divided into two great groups, — hard and soft. Aside from certain 

 external criteria, — for the most part unreliable, — the two groups may 

 be differentiated by the following characters. Hard pines have 

 sculptured ray tracheides, two or more rows of resin canals in the first 

 annual ring, sclerified pith (except most of the two-needled varieties) 

 and lack tangential pitting (except in the first few year's growth and 

 the cone axis). Soft pines on the other hand, have smooth walled ray 

 tracheides, a single row of resin canals in the first annual ring, tangen- 

 tial pitting, anfl lack stone cells in the pith. On all four of these fea- 

 tures, our lignite belongs with the hard pines, and since it is the earliest 

 known completely differentiated hard pine, we propose for it the name 

 of Pinus protoscleropihjs. In using the generic name Pinus rather 

 than Pityoxylon, we are following the example set by Conwentz and 

 Bailey, since the specimen in question cannot be separated anatom- 

 ically from living pines. 



