No. 2.J SHUFELDT ON NORTH AMERICAN TETRAONID^E. 349 



line, as it does not occur in this bird; PI, palatine; mx, maxillary; i. mx, intermaxillary 

 (or premaxillary) ; 1, the petrosal ; 2, the sclerotals ; 3, the lacrymal; Piy, the ptery- 

 goid, the diverging appendage of PI, the palatine ; sq and ma, the squamosal and 

 vialar, respectively, are diverging appendages of Tp, the tympanic. 



PLATE VI. 



Fig. 52. — Lateral view of skull of Centrocercus, adult g , hyoid arch removed. Figs. 

 54, 55, 58, 61, G4, 65, 66, 68, 69, and 70 are from the skeleton of the same specimen. 



Fig. 53. — Sternum of the chick, three or four days old ; Centrocercus. 



Fig. 54. — Sternum of Centrocercus, viewed from below ; adult ^ . 



Fig. 55. — Dorsal vertebrae, lateral view, left side, from the same. 



Fig. 56. — Sternum of Centrocercus, "bird of the year" (two months old), showing 

 develoijment of this bone : 4, lophosteon; 5, metosteon; 6, pleurosteon. 



PLATE VII. 



Fig. 57. — Right pectoral limb of Centrocercus, same bird as the sternum in Fig. 56 

 was taken from. H, humerus, palmar aspect ; r, radius ; u, ulna ; s, scaphoid (ra- 

 diale); c, cuneiform (ulnare); z, unciform; d, index digit; 9, third metacarpal (an- 

 nularis) ; 9', second metacarpal (medius) ; d', d", phalanges of the second metacar- 

 pal ; d" ', phalanx of the third metacarpal. 



Fig. 58. — Left metacarpus of an adult Centrocercus. 



Fig. 59. — Left metacarpus of the same bird as figured in 57, showing all the seg- 

 ments that go to make up the boce in Fig. 58 : om, carpale or os magnum ; z, unci- 

 form ; 7, index or first metacarpal ; 8, pisiform ; 9', second metacarpal ; 9, third meta- 

 carpal (annularis). 



Fig. 60. — Left humerus {Centrocercus), taken from the same bird as in Fig. 57. 



Fig. 61. — Left humerus, anconal aspect, Centrocercus; adult. 



Fig. 62. — Ossa innominata, Centrocercus, three or four days old, showing how the 

 pelvic bones form the acetabulum : X, ilium ; Y, ischium ; Z, os iiubis. 



Fig. 63. — Pelvis, same bird as in Fig. 57; Centrocercus; X, ilium; Y, ischium; Z, 

 OS pubis. 



Fig. 64. — The perfect pelvis, lateral view, as in 62 and 63, of Centrocercus; adult ^ . 



PLATE IX. 



Fig. 65. — Posterior view of pygostyle, adult Centrocercus. 



Fig. 66. — The same, left lateral view. 



Fig. 67. — Pelvic limb, anterior view, Centrocercus, taken from same bird as in Fig. 

 57: E,E;picnem,ial epixiJiysis oi the tibia; E', the confluent tarsal bones found at the 

 distal extremity of the tibia at this age, tibiale (astragalus), and fihulare (os calcis) ; 

 E ' ', the centrale. 



Fig. 68. — Left tarso-metatarsus, inside view, adult <? , Centrocercus. 



Fig. 69. — Anterior view of right tibia and fibula, from the same skeleton as 68. 



Fig. 70. — Anterior view of right femur, same bird as shown in Figs. 68, 69. 



PLATE X. 



Fig. 71. — Right lateral view of skull of adult <? Cupidonia cupido. 



Fig. 72. — Lower mandible from the same, viewed from above. 



Fig. 73. — Skull from the same, lower jaw removed; seen from above. 



Fig. 74. — The same from below. 



Fig. 75. — Sclerotals, right eye from the same. 



Fig. 76. — Right humerus, from the same, jjalmar aspect. 



Fig. 77. — The same, anconal aspect. 



