OF THE MARSUPIALIA, EDENTATA, AND SIRENIA. 187 



usual manner, and crystals formed readily at room temperature, showing 

 no signs of dissolving. They were oxyhemoglobin, as shown by the spec- 

 troscope. 



Oxyhemoglobin of Petrogale sp. 



Monoclinic: Axial ratio not determined. /? about 84 (96). 



Forms observed: Orthopinacoid (100), clinopinacoid (010), prism (110), base (001). 



Angles: 100 A 001=/?=84; 001 A 010=90. 



Habit lath-shaped by development of the two vertical pinacoids (100) and (010) 

 and terminated obliquely by the base (001) (text figure 98), also prismatic with the com- 

 bination of prism (110) and base (001) (text figure 99). The crystals are capillary in 

 some cases (probably the prism and base combination) ; and in other cases are long lath- 

 shaped, with the orthopinacoid predominating, and then with square ends (text figure 

 98); or short lath-shaped, with the clinopinacoid predominating (text figure 100), and 

 then with oblique ends. The prism seems to be nearly square, but its angle could not 

 be obtained. Contact twins on the orthopinacoid (gypsum type) are common (text 

 figure 101) ; twins on a pyramid of the interpenetrant type were also observed (compare 

 text figure 97). 



Pleochroism is rather strong; a pale yellowish-red, 6 red, c deep cochineal-red. 

 Extinction was apparently straight in both aspects, on (100) and on (010), the side and 

 edge views. The orientation of the elasticity axes is a =6; b A a =6, in the obtuse 

 angle; c=<J; the axial plane is hence normal to the plane of symmetry. No interference 

 figure was observed, but evidence of the brushes was noticed on the side and edge views, 

 which points to Bx a =c, and the optical character is hence probably positive. 



It will be noticed that the crystals that show flattening on the ortho-axis are flat- 

 tened along the axis of greatest elasticity; this is to be expected, as they developed 

 later and hence under greater pressure, and this axis should be most sensitive to the 

 increase of pressure. 



EDENTATA. 



ANT-EATER, Myrmecophaga (?). Plate 23. 



The specimen of blood was received from the National Zoological 

 Park at Washington. The corpuscles were separated, oxalated, ether- 

 laked, and centrifugalized, and preparations made in the usual manner. 

 The crystals formed readily and were kept in the cold, as they showed a 

 tendency to dissolve when brought into the room. After 24 

 hours they began to dissolve, even in the cold, especially the crys- 

 tals in the protein ring; the solution beginning with the ends of 

 the crystals, which lose their sharp outlines and become rounded. 

 By the spectroscope these crystals were determined to be oxy- 

 hemoglobin. 



Oxyhemoglobin of Myrmecophaga (?) . 



Orthorhombic : Axial ratio a : <5 = 1 : 0.4348. ' "* 



Forms observed: Brachypinacoid (010), macropinacoid (100), macro- 

 dome (101), basal pinacoid (001). 



Angles: Macropinacoid to macrodome, 100 A 101 =66 30'; dome to 

 dome faces 101 A 101=47 (133); macropinacoid to base 100 A 001=90. 



Habit long lath-shaped, flattened on the brachypinacoid; the macro- , M 



pinacoid very narrow, and the crystal terminated by a macrodome or by 

 the base (text figure 102). The crystals are capillary or even acicular and FIO. 102. 

 sharply pointed when first forming, but the terminations become distinct ^^. 

 as the crystal grows. The first-formed crystals show less of the brachy- 

 pinacoid (010) than those that are fully developed. In the fully developed crystals it is 

 seen that they thin on the plane (010) towards the ends of the crystals, by development 

 of (Oml). Cleavage is apparently basal. 



