178 THANS. ST. LOUIS ACAD. SCIENCE. 



* Cones subterminal ; leaves in threes to fives. Euaustrales. 

 P. oocarpa,'^^ occidentalism ausiralis.^'^ 



* * Cones lateral or mostly so ; leaves in twos to threes. El- 



liottiir. 

 P. Elliot tii,^^ Cubensis,*^ Wright ii.^^ 



NOTES. 



1. p. Pence, Griseb., may after all be distinct from P. excelsa\ it has 

 much shorter leaves and sheaths, and, if my specimen can be relied on, a 

 shoi't fruiting peduncle ; the structure of the leaf is nearly the same in both. 

 P. Pence, excelsa, and rnottticola have a layer of strengthening cells all 

 around under the epidermis, interrupted only by the stomata, and not in 

 distinct bundles as in Lambertiana and Bonapariea, while P. Strobus, 

 Ayaca/iuite, and parvijiora, have scarcely any. They all have regularly 

 two dorsal ducts only. In P. excelsa I have repeatedly found a third, 

 upper, and always a parenchymatous one. 



2. P. parvifiora, Sieb. & Zucc. A branch in Herb. Haenke in the 

 Prague Museum, marked "P. heteroykylla, Presl, Nutka Island," seems to 

 belong to this species, which is distinguished by slender, distantly and 

 very slightly serrulate leaves, and scarcely any strengthening cells. 



3. P. Botiapartea, Roezl. Prof. E. Purkinje, of the Foresters' Academy 

 of Weiswasser, Bohemia, who was probably the first to carefully study the 

 microscopic anatomy of the pine-leaves with a view to the diagnosis of the 

 species, and who is now publishing the results of his investigations in an 

 extensive and copiously illustrated work, has directed my attention to the 

 leaf-structure of this form. It deviates from all the other Strobi in having 

 numerous, usually 7, ducts, 3 on the back and 2 on each of the upper sides, 

 and having strengthening cells in numerous bundles all around and espe- 

 cially in the angles. I find no stomata on the back. Roezl's P. Don Pedri 

 has exactly the same structure, but has 3 or 4 series of stomata on the 

 back; both evidently belong together. Though I have not been able to 

 study the flowers and fruit, I do not hesitate to pronounce it distinct from 

 P. Ayacakuite, which, like P. Strobus, has scarcely any strengthening 

 cells, and only 2 dorsal ducts. 



4. P. Cembra, Lin. The ducts, generally in the middle of the paren- 

 chyma, sometimes nearly approach the epidermis, but I have always found 

 them separated from it by at least one layer of parenchymatous cells. 



5. P. monopkylla, Torr. & Frem. The number of ducts is excessively 

 variable; I have found from 3 to 14 in different leaves. The leaves are 

 usually curved, and the upper side, proved to be such by the relative posi- 

 tion of the wood and bast cells (see p. 165), is always directed towards 

 the branch. Sometimes two-leaved bundles occur. It is an open question 

 whether the four species of the subsection Cembroides may not properly 

 be united into one, as the difference of flowers and fruit is very slight, and 

 that of the foliage only relative. 



