OTARinXE, PHOCID.E, MUSTELID^E, PROCYONID.E, AND URSID^. 257 



Oxy 'hemoglobin of Cercoleptes caudivolvulus. 



Orthorhombic : Axial ratio, a : b : 6 =0.6556 : 1 : 0.4663. 



Forms observed: Unit prism (110), brachydome (Oil), brachypinacoid (010), 

 base (001), macropinacoid (100). 



Angles: Prism angle 110 A 1TO=66 30'; brachydome angle 01lAOTl=50; 

 brachypinacoid to brachydome 010 A 011=65; base to macropinacoid 001 A 100=90. 



The crystals occur in two habits: (a) prismatic along the vertical axis, the crystal 

 consisting of the unit prism (110), brachydome (Oil), and brachypinacoid (010) (text 

 figure 278) ; (b) tabular on the brachypinacoid, the crystals apparently consisting of 

 the three pinacoids (100, 010, and 001) (text figure 279). Type (a) is the common crystal, 

 and the crystals of the type (b) only appeared sparingly in the slides. The type (a) 

 crystal is usually quite symmetrically developed, the planes (110) and (Oil) being large, 

 but the plane (010) generally small. The dome termination is liable to develop with 

 two faces, usually on the same side (as Oil and Oil), larger than the opposite pair; some- 

 times the larger pair are diagonally opposite each other. This unsymmetrical develop- 

 ment occasionally goes so far as practically to suppress two of the dome faces, when the 

 crystal has a monoclinic appearance. The ratio of length to thickness of the prism, 

 comparing the length to the longer diagonal of the prism section, is usually about 5 : 1 

 and runs down to 2 : 1 or less. Definite twinning was not observed, and the crystals 

 occur singly or simply massed together in irregular order. These type (a) crystals are 

 very smooth and perfect and show no striation. The type (b) crystals appeared sparingly 

 in the slides and were either nearly square plates or long lath-shaped crystals. The 

 latter form aggregated in bundles or groups with parallel orientation, but not so regular 

 as parallel growths; the square habit piled up on the brachypinacoid in parallel growth. 

 This type (b) crystal seemed to be somewhat more soluble than the other type, losing 

 its angles and especially the ends of the long lath-shaped crystals by solution, but this 

 was probably due to the fact that they were very thin and hence showed solution cor- 

 rosion sooner than the crystals of the other type. Apart from the parallel growth, these 

 crystals showed nothing of the nature of twinning. 



278 



279 



280 



Flos. 278, 279. Cercoleptet caudivolvulus Oxyhemoglobin. FIGS. 280, 281, 282. Batsaritcus astuta Oxyhemoglobin. 



Pleochroism is strong when viewed on the brachypinacoid aspect in both types of 

 crystals, but practically absent when looking along the brachy-axis. The colors are: 

 a pale yellowish-red to pinkish; b and c equal and deep red. Extinction is straight in 

 all aspects. No interference figure was observed. The orientation of the elasticity axes 

 is a =a, b =b, c = t. From the character of the double refraction (very weak when 6 and c 

 are in the section and strong when either b or c and a are in the section) and from the 

 pleochroism, it is evident that the axis of greatest elasticity is the acute bisectrix, Bx a = a, 

 and the optical character is hence negative. 



17 



