28 Evans . — Branching in the Leafy Hepaticae. 
extent may be seen. The branches are situated in the axils of the leaves 
and show a distinct basal sheath. In the majority of cases, as in the branch 
on the right, the first leaf is basiscopic with respect to the main axis, the 
second leaf is an underleaf, and so on. In the figure the first leaf is only 
partially visible and is considerably displaced from its theoretical position. 
In the branch on the left it will be noted that the first leaf is acroscopic, 
and cases may also be found where the first leaf is an underleaf. The main 
axis in the figure is sinistrorse, the branch on the right is dextrorse. Other 
cases were observed, however, in which dextrorse spirals occurred in branches 
on the left and sinistrorse spirals in branches on the right. So far as can 
be learned the spiral of the main axis exerts no influence upon the spirals 
Fig. 34. Micropterygium Plerygophyllum. 
Mabess River, Jamaica {A. W. E., No. 316). x 40. 
of the branches. In the genera Scapania, Diplophylleia , Sphenolobus , and 
Cephaloziella (subgenus Prionolobus ) the leaves are bilobed and more or less 
complicate, but their lobes are both attached to the axis. With the 
exception of certain species of Cephaloziella none of these genera produce 
underleaves. Their lateral intercalary branches are distinctly axillary and 
resemble in most essential respects the branches of Micropteryginm . 
The other genera, where lateral branches are here interpreted as inter- 
calary, are all distinguished by succubous undivided leaves. Plagiochila 
Snllivantii, a species of the eastern United States, shows the usual conditions 
present (Fig. 35). The branch figured is borne in the axil of a leaf but 
close to the ventral margin, and an examination of Chiloscyphus will show 
that the female branches arise in much the same position. Apparently in 
branching of this kind there is more or less variation in the relative positions 
