Io TRANS. ST. LOUIS ACAD. SCIENCE. [1 70 
The carpellary scales, which in the flower as well as in the 
fruit we call, in short, scales, are either rounded, obtuse, and 
appressed (in Strodus, etc.), or they have a short (P. resinosa, 
sylvestris, etc.) or a longer (P. ponderosa, Twda) or an elon- 
gated subulate, often squarrose, point (P. contorta, inops, 
pungens). 
The aments are globose, oval or elongated, subsessile or pedun- 
cled, single or several together, always erect, each borne in the 
axil of a bract, its base invested by sterile bracts which gradually 
or suddenly give place to the carpel-bearing bracts, just as the 
involucral scales of the male flowers give place to stamens. They 
make their appearance on the upper part of the year’s shoot, 
often just below the terminal bud, when we call them sudéer- 
minal; or they become /ateral, when the axis elongates beyond 
them, and sometimes more aments form above them in the same 
season. The axis above the aments continues covered with leaf- 
bundles in some, while in others it is naked for some distance, or 
rather destitute of leaves, bearing only bracts; a second stage 
of aments or the terminal bud is always preceded by a number 
of leaf-bundles. 
The position of the female ament, whether subterminal or late- 
ral, seems to be connected with an essential difference in the spe- 
cies of pines, secondary in importance only to the leaf structure as 
described above, and both of these together will enable us to ar- 
range the species in something like a natural order. It ought to be 
understood, however, that the relative position of the ament on the 
axis is not absolute and that variations do éccur. Species with or- 
dinarily subterminal aments may in young and vigorous shoots 
sometimes bear lateral aments; this occurs, though very rarely, 
in P. ponderosa and australis, and perhaps in others, but I have 
never seen it in any of the S¢rodus section, nor in P. sylvestris, 
restnosa, Laricio or its allies. More frequently subterminal 
aments are found in species which normally bear lateral ones, 
probably when with the formation of the aments the vigor of the 
axial growth has been exhausted; thus sometimes a second stage 
of aments is.subterminal, while the first is of course lateral; or 
subterminal and lateral ones are occasionally found on differ- 
ent branches of the same tree; or, very rarely, a tree bears al- 
most entirely subterminal aments. This last case I have seen in 
