56 being both composed of the pinacoid, a brachydome, and macrodome, with sign 0P 
the variation in aspect arising from the predominance of different faces; and fig. 57 consisting of the macro-dome
the prism 
and the pinacoid 0P.
V. The Monoclinohe-dric System.—This
system is characterized by three unequal axes, two of which intersect
eacli other at an oblique angle, and are cut by the third at right
angles. One of the oblique axes is chosen as the chief axis, and the
other axes are then distinguished as the orthodiagonal (right-angled)
and clino-diagonal (oblique-angled). The same terms are applied to the
chief sections, and the name of the system refers to the fact that
these two planes and the base, together with two right angles, form
also one oblique angle C. —
The
forms of this system approach very near to those of the rhombic series,
but the inclination of the axes, even when almost a right angle, gives
them a peculiar character, by which they are always readily
distinguished. Each pyramid thus separates into two altogether
independent forms or hemipyramids. Three varieties of prism also
occur,—vertical, inclined, and horizontal,—with faces parallel to the
chief axis, the elinodiagonal or the orthodiagonal. The horizontal
prisms, like the pyramids, separate into two independent partial forms,
named hemrprisms or hemi-
3
