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



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

 (or promaxillary); 1, the iietrosal ; 2, the sclerotals ; 3, the lacrymal ; P<^, the ptery- 

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

 malar, 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, Gl, 04, 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 oi Centrocercus, "bird of the year" (two months old), showing 

 development of this bone : 4, lophosteon; r^, metosteon ; G, 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 metacariial (an- 

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

 pal ; fZ" ', 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 bone 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 pubis. 



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

 08 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,Epicncmml epiphysis oi Wxetihia; E', the confluent tarsal bones found at the 

 distal extremity of the tibia at this age, iibiale (astragalus), and jlbulare (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 63. 



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, palmar aspect. 



Fig. 77. — The same, anconal aspect. 



