28 TRANS. ST. LOUIS ACAD. SCIENCE. [188 
regularly laminated, and the outer laminz exfoliate in rather rigid 
and brittle, often very thin, plates of a purplish color when fresh, 
whence the local name of Blue-pine ; the bark of P. australis is 
somewhat similar, but the plates are much larger. 
The timber is excellent, heavy, very tough, and more resinous 
even than that of P. australis, which it resembles; of a striped 
yellowish-brown and paler resin color (the inner portion of 
each ring, formed earlier in the season, being paler; the outer 
part, of later growth, brown); fibre coarser than in australis 
and more tenacious. It grows rapidly, at least in its youth: 
a tree of 22 inches diameter, and about 140 years old, had in the 
semi-diameter 8} inches of heartwood with 74 annual rings, and 
white sapwood 2} inches thick with 60 to 70 rings; another 
of over 3 feet diameter, 109 feet high, and 200 years old, had a 
radius of 17 inches heartwood with about 140 rings, and 3 inches 
of sapwood of 60 rings. Thus the average rings of the heartwood 
were over 1} lines and those of the sapwood (because of later 
growth) about 3 line wide. The leaves of young trees are more 
frequently in twos, in older ones as often in threes; those of trees 
from swampy soil are apt to be shorter than others ; the structure 
in all of them is the same. 
Our species is closely allied to P. Cubensis (see p- 185), and 
_ further study of the latter may possibly prove them to be nothing 
but geographical varieties. Meanwhile the constantly three-leaved 
foliage, the larger number of involucral bracts of the smaller male 
flowers, the smaller cones with smaller, shorter-winged seeds, 
distinguish P. Cudensis from our species. Of the bark, of the 
timber, or of the behaviour of the young cones in this species we 
know nothing. 
P. Eliiottii was imperfectly known to Elliott, and was consid- 
ered by hima form of P. Zieda. Later botanists ignored it till Dr. 
_ J. H. Mellichamp of Bluffton, S. Car., rediscovered it about ten 
years ago and directed my attention to it. Without his diligent 
investigations, ample information, and copious specimens, this 
paper could not have been written. At the same time I grate- 
fully acknowledge my obligations to many botanical friends in 
this country and in Europe, and especially to the directors of the 
