2 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Schizognathous, holorhinal, terrestrial, or arboreal rasorial birds with 

 sternum usually deeply 4-notched or cleft (2-notched in Opisthocomi) ; 

 16-19 cervical vertebrae (19 in Opisthocomi, 16 in all the rest) ; cora- 

 coids without a subclavicular process and with basal ends overlapping or 

 crossed; quadrate bone double; intestinal convolutions of type V (plagio- 

 coelous) ; bill relatively short, with maxilla vaulted, its tip overhanging 

 that of the mandible, vaulted, not compressed, and with hallux always 

 present. 



Nares holorhinal, impervious ; palatines without internal lamina ; max- 

 illopalatines not coalesced with one another or with the vomer^ ; quadrate 

 bone double; basipterygoid processes absent but represented by sessile 

 facets on anterior part of sphenoidal rostrum; rhamphotheca simple; 

 angle of mandible produced and recurved. Cervical vertebrae, 16; an- 

 kylosed sacral vertebrae preceded by a free vertebra, this by four anky- 

 losed dorsal vertebrae, the latter heterocoelous ; coracoids with or without 

 (Opisthocomi) a subclavicular process and with basal ends overlapping 

 or crossed; furcula with median process (hypocleidium) much developed. 

 Metasternum with four deep notches or clefts (Galli), or two notches 

 (Opisthocomi), in the former case the median xiphoid process very long 

 and narrow, the internal processes much shorter, the external processes 

 shorter still and bent outward over posterior ribs, their extremities ex- 

 panded; spina communis sterni and processus obliquus present, large; 

 episternal process perforated to receive a process from base of coracoids ; 

 muscle formula usually ABXY-|-(the femorocaudal muscle absent in Pavo 

 and Meleagris, very slender in Cracidae) ; expansor secundariorum pres- 

 ent, but in Tetrao, Francolinus (except F. clappertoni), RoUulus, Euplo- 

 comus, Gallus, Ceriornis, and Pavo, instead of being inserted into the 

 scapulosternal fibrous head, after blending more or less with the axillary 

 margin of the teres, it ceases by becoming fixed to a fibrous intersection 

 about one-third way down the coracobrachialis brevis muscle ; biceps slip 

 usually present (absent in Ortalis araucuan, Crax, Mitua, Talegallus, and 

 Numida, but present in Megapodius and Megacephalon) ; tensor patagii 

 brevis with a thin, wide, diffused tendon (as in Crypturi) ; ectepicondylo- 

 ulnaris muscle present (as in Crypturi) ; anconeus with humeral head not 

 always present; gluteus primus present, large; gluteus V present (ten- 

 dinous in Chrysolophus pictus) ; intrinsic syringeal muscles absent ; deep 

 plantar tendons of type I (if reaching the hallux proceeding from flexor 

 longus hallucis, not from flexor perforans digitorum). Intestinal convo- 

 lutions of type V (plagiocoelous) ; crop present, globular ; stomach usu- 

 ally a gizzard (Centrocercus the only known exception) ; gall bladder 

 present ; caeca large ; oil gland usually tufted (nude in Megapodii, absent 



' In some Cracidae, however, the maxillopalatines are said to be united medially 

 into an ossified septum. 



