. Carnegie Institution of Washington publication. OF THE CATS AND CIVETS. 297 some cases only one parallel pair show at all, when the crystal looks monoclinic. Type (b) tabular on the base, with the brachyprism (120) and the base only developed (text figures 354 and 355); in these the length of the prism may be one-fourth of its short diagonal. These type (b) crystals are rather rare. Type (c), the unit prism (110) and the base (text figure 356); these are rare; when the dome appears instead of the base, the crystal looks like a rhombohedron. Aside from the tendency of the crystals of type (a)
. Carnegie Institution of Washington publication. OF THE CATS AND CIVETS. 297 some cases only one parallel pair show at all, when the crystal looks monoclinic. Type (b) tabular on the base, with the brachyprism (120) and the base only developed (text figures 354 and 355); in these the length of the prism may be one-fourth of its short diagonal. These type (b) crystals are rather rare. Type (c), the unit prism (110) and the base (text figure 356); these are rare; when the dome appears instead of the base, the crystal looks like a rhombohedron. Aside from the tendency of the crystals of type (a) to unite on the prism faces in parallel growth or to grow along the macro-axis in the same kind of arrangement, aggregate crystals with regular arrangement do not appear to occur; no undoubted twins were observed. The crystals are of the typical reduced-hemoglobin color and show marked pleo- chroism; a pale rose-pink or pale lilac, b rose-red, c deep purplish-red. Extinction is straight or symmetrical; and in the unsymmetrical, monoclinic-looking crystals it is parallel to the prismatic zone. Double refraction is strong. On accidental cross-sections of the prism, or on the tabular crystals of type (b) when the basal aspect is presented, the biaxial interference figure is seen in convergent light. The orientation of the elas- ticity axes is a=a; b=b; (=6. The plane of the optic axes is the brachypinacoid; and the acute bisectrix of the optic axes is the axis of least elasticity, Bxa = c. The angle of the optic axes is wide, 2E=82°. The optical character is positive. ^-Reduced Hemoglobin of Lynx canadensis var. Tetragonal or pseudo-tetragonal. No axial ratio was determinable. Forms observed: The only forms seen were the unit prism (110) and the base (001). Angles: The prismatic angle was 90°, as nearly as it could be observed; and a like angle was measured from the prism to the base. Habit short prismatic, cubical, or sometimes rhombohedral-looking crystals. The apparent prism
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