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, Bx a = 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 was in equilibrium with the base or somewhat longer, with a ratio of 

 length to thickness of 1 : 1 or 3 : 2 (text figure 357) . 



The crystals were not very strongly pleochroic. Extinction took place in the 

 direction of the prism axis. On cross-sections showing the basal aspect, the crystals 

 were singly refracting. When this aspect was presented, a uniaxial cross was seen. The 

 vertical axis is the axis of least elasticity, and the crystal is hence optically positive. 



Except for the uniaxial character of these crystals they closely resemble crystals 

 of type (c) of the a-reduced hemoglobin. They occurred very sparingly in the slides. 



Oxyhemoglobin of Lynx canadensis var. 



Orthorhombic: Axial ratio a : b : 6 =0.9657 : 1 : 6. 



Forms observed: Unit prism (110), base (001), brachy- 

 pinacoid (010), macropinacoid (100). 



Angles: Unit prism 110 A 110 = 88; pinacoids 110 A 

 010 = 90. 



Habit very thin tabular on the base, the crystal con- 

 sisting of the base (001) cut by the unit prism (110) and 

 sometimes also by the two vertical pinacoids (100) and 

 (010) (text figures 358 and 359). The crystals grow in 

 groups on the base; also in radiating tufts and spheroidal 

 masses, by growing together on the base, or in the zone of 

 the base and one of the vertical pinacoids. They are fre- 

 quently curved, at least in the groups, and when seen on 

 edge form various arborescent shapes. Sometimes, when FlQ8 ' 35 oxyhem^gi^Jn." a 

 on edge, they present the appearance of radiating rods. 

 They were only found in the slides for about 24 hours after the preparations were made. 



The color was the usual scarlet-red of oxyhemoglobin. The crystals were not 

 noticeably pleochroic and did not have sufficient thickness to polarize, so that definite 

 optical characters could be determined. (See plate 92, figs. 551 and 552.) 



