276 ME. W. P. PYCEAFT ON THE MOEPHOLOGT AND 



a'. Width between inner angles of articulation for last sternal rib less than 



width across metasternum at widest C casuarius. 



b'. Width between inner angles of articulation for last sternal rib greater 



than width across metasternum at widest C. c. beccarii. 



b. Coracoid grooves shallow, lower lip not strongly marked when seen from 



above ; mouth of the pneumatic aperture produced forward into prominent 



lips; anterior lateral process short and recurved. Metasternal region 



very long and narrow. 



c'. Width across anterior lateral processes of sternum twice width of 



metasternum . C. bennetti. 



d'. Width across anterior lateral process of sternum less than twice width 



across metasternum C. picticollis. 



D. Pelvic Abch K (PI. XLIV. fig. 5.) 



Synsacral neural spines of great height ; sacral vertebrae, and sometimes the last lumbo-sacral, 

 and first and second caudals with conspicuous pleurosteal elements ; pre-acetabular ilia always 

 meeting in the mid-dorsal line above the neural spines of the synsacrum ; the synsacral neural 

 spines never projecting beyond the level of the post-acetabular ilia ; ilio-ischiadic fissure either 

 permanently open or closed only by the fissure of the extreme ends of the ilium and ischium. 



A. Pubes remaining permanently free caudad. 



a. With the post-acetabular ilia more or less widely separated in the mid- 

 dorsal line ; a more or less well-developed supra-trochanteric process. 

 a'. Post-acetabular ilia separated by the intervention of the synsacral neural 

 spines ; ischia bowed inwards towards the middle line, and fused 

 posteriorly with the ilium ; perforation of inner wall of acetabulum 

 constricted by ossification. 

 a". Post-acetabular longer than pre-acetabular ilium, and tapering 



gently Dromceus. 



b" . Post-acetabular shorter than pre-acetabular ilium, and arched 



dorsally Casuarius. 



b'. Post-acetabular ilia widely separated by means of transverse processes, 



leaving neural spines in middle of a deep fossa roofed in late in life by 



a sheet of bone ; ischia widely separated one from another and from 



post-ilia ; post-acetabular with a very wide dorsal plane. 



c". Median fossa dividing post-acetabular ilia only imperfectly roofed 



in, leaving a more or less extensive cleft on either side of a broad, 



flat neural plate Dinornithides. 



d' 1 . Median fossa dividing post-acetabular ilia completely roofed by bone, 

 but perforated by a double row of foramina, one on either side of 

 the median line JEpyornis. 



1 The pelvic arch of the Crypturi will he found described on p. 263. There was no need to include it 

 here. 



