OTARIID^E, PHOCID.E, MUSTELID^E, PROCYONHXE, AND URSID^E. 261 



case of the black bear, the crystals of the first crop were mostly trillings, 

 and those of the second crop were mainly single, untwinned crystals. The 

 color of the blood and of the crystals was decidedly brownish, but the spec- 

 trum was that of oxyhemoglobin. The solution probably contained met- 

 oxyhemoglobin, which seems to be common in bear blood, at least during 

 the winter. 



Oxyhemoglobin of Ursus maritimus. 



Monoclinic heinimorphic (monoclinic sphenoidal): Axial ratio a : b : 6 =1.2088 : 

 1 : (5; /? = 732' (calculated). 



Forms observed: Unit pyramid (Til), imperfectly developed; unit prism (1TO), 

 prism (230), in twins only; basal pinacoid (001); also rarely (100) ? or (101). 



Angles : Traces of the unit prism on the base, edges 110-001 A TlO-001 =79 12', 

 average of a number of measurements; 110 A 001=77 (about); Til A 001 =48 30'. 

 The angle of the dome (101), or orthopinacoid (100), on the base was not determined. 



290 



FIGS. 288, 289, 290. UTSUS maritimua Oxyhemoglobin. 



Habit tabular on the base, the crystal consisting of the basal pinacoid (001) cut 

 by the unit prism at one end of the ortho-axis and by the unit pyramid at the other end 

 (text figures 288 and 289). The first crystals to form are of this habit, porous-looking 

 tabular crystals that are proportionately rather thick, but they do not attain very large 

 size. They are usually in trillings as already described for the black bear oxyhemo- 

 globin (text figures 286 and 287) and this kind of twinning is normal in the bears. As 

 these crystals of the first crop disappear, they are succeeded by crystals of the second 

 crop, in which the base (001) and the unit prism (110) are well formed, and usually have 

 sharp angles and smooth faces; but the unit-pyramid planes are generally imperfect in 

 these second-crop crystals. Nevertheless, the angle of the unit pyramid on the base 

 was obtained from crystals of the second crop. The tabular crystals of the first crop 

 are proportionately much thicker than those of the second crop, the ratio of the long 

 diagonal of the plate to its thickness being about 5:1; while in the second-crop crystals 

 this ratio will average nearer to 25 : 1. The crystals of the second crop produce parallel 

 growths, but do not twin, as do those of the first crop. A few crystals were observed in 

 the second crop that were prismatic on the ortho-axis, by development of planes in the zone 

 100-001, which seemed to be (100) or (101), and (001) (text figure 290); but the angle 

 on the base was not measurable, owing to the position in which the crystals were lying. 



Pleochroism was rather marked in positions where the axis of greatest elasticity 

 appeared in the section; the colors were: a nearly colorless, b and c about equal and deep 

 red, somewhat brownish-red. The crystals of the first crop, which look soft and porous, 

 do not show as strong double refraction as those of the second crop; the extinction on 

 the flat is symmetrical with the outline of the plate; on edge views of the plate the extinc- 

 tion runs up to 20 with the axis a, or the long dimension of the plate. The orientation 

 of the elasticity axes is c A a =20, in the obtuse angle; 6=6, a A 6 = 6' (calculated); 

 or a is parallel to A as nearly as can be measured. On the flat aspect, in convergent light, 



