274 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
C. Srernum (fig. 4, p. 217) AnD Pecrorat ArcH?. 
The sternal plate is keelless; the coracoid anchyloses with the scapula, and lacks the acro- 
coracoid, the coraco-scapular angle is very wide ; furcula vestigial or absent. 
A. Coracoid grooves not widely separated. 
a. Metasternum pointed, no posterior lateral processes; pro-coracoid not 
forming a distinct bar. 
a’. Coracoid grooves and bases of coracoids overlapping ; anterior lateral 
process long, directed upwards and backwards ; a pair of short recurved 
processes lying on the anterior sternal border between the anterior 
lateral processes ; with vestigial clavicles ; sternal plate nearly as broad 
as long; coracoid longer than broad . . . - . se . . . Dromeus. 
2/. Coracoid grooves not overlapping ; anterior lateral processes of sternum 
short or obsolete ; no clavicles ; sternal plate much longer than broad; 
coracoid as broad aslong . . .- Hed sare ees aly \Casuanme: 
b. Metasternum more or less pointed, with hive ostceiae lateral processes ; 
pro-coracoid of great size, forming a distinct bar of bone ; body of the 
sternum with a conspicuous ventral prominence ; no clavicles ; articular 
surfaces for ribs of great width . 2. 2. + ee + + + + + + Struthio. 
B. Coracoid grooves widely separated. 
a. Corpus sterni basin-shaped with a marked poreedl prominence ; posterior 
lateral processes absent ; anterior lateral processes conspicuous, each with 
a large pneumatic aperture at the base; articular surfaces for ribs 
crowded together immediately behind the anterior lateral processes ; 
coracoid grooves at the base of the anterior lateral processes and separated 
one from another by the wide emarginate body of the anterior border of 
the sternum ; coracoids long and slender ; pre-coracoid relatively small. Rhea. 
b. Sternal plate flat, slightly or not at all pneumatic ; metasternal and posterior 
lateral processes always present ; facets for ribs not separated by deep 
pneumatic pits. 
a’. Articular facets for ribs widely spaced, and lying entirely behind the 
anterior lateral processes, and not separated by deep pneumatic pits ; 
coracoid nearly as broad as long ; pre-coracoid not conspicuous. . . Apteryx. 
b/. Facets for ribs crowded, few in number, and partly underlying the base 
of the anterior lateral processes ; coracoid extremely reduced . . . Dinornithide. 
C. Sternal plate flat, pneumatic ; metasternal element wanting ; facets for ribs 
separated by deep pits; sternal plate exceedingly narrow from before 
ickewardSi. Le ss 6.4), <i stele eit eueeitd oh ele ueioarts Siete Ma ecdaee PY OTT. 
The sternum and pectoral arch of the Crypturi will be found described on pp. 221 & 263. 
