AXIAL SKELETON OF THE STRUTHIONIDA. 45 
may be three in number; or they may probably be only two, as appears to be the case 
in D. elephantopus. 
THE STERNUM. 
The sternum of Dinornis is, as it were, an exaggeration of the sternum of Apteryx. 
The coracoid-grooyes are all but obsolete, so exceedingly faint is the concavity formed 
by them on the costal angle. The pleurosteon is reduced to a small irregular surface 
postaxiad of the root of the costal angle, and may bear three articular surfaces, as in D. 
rheides and D. didiformis, or only two, as in D. elephantopus. There is no preaxial 
median process, groove, or fossa; but one straight rounded surface bounds the sternum 
preaxially. The costal angles are of moderate size. The lateral xiphoid processes are 
very prolonged and slender, extraordinarily so in D. rheides. They may be directed 
postaxiad in an almost parallel direction, as in the last-mentioned species; or they 
strongly diverge postaxiad as in D. elephantopus. The median xiphoid process is very 
large, and, of course, separated from the lateral xiphoids by great notches. It may be 
very wide at its root, as in D. elephantopus, or rather narrow as in D. rheides. It has 
always a more or less pointed postaxial termination. 

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Struthio. Rhea. Dromeus. Casuarius. Apteryz. Dinornis. \ Struthionide. | 
Number of cervical 
vertebre ...... 17 14 17 (or 18)| 14-16 15 15 14-17 
Cervico-dorsal .... 3 3 3 4-3 1 3 14 | 
Both together .... 20 17 20 (or 21) | 19 (or 18) 16 18 16-21 | 
Mongallees. 2/9 spsea 5 3 4 5) 4 3 (or 2) 2-5 | 
Dorso-lumbar .... 2 3 2 2 (or 3) 4 3 2-4 
Dorsal and dorso- | 
lumbar together . 7 6 6 7 (or 8) 8 6 | 6-8 
All the first four ca- = 26 (or 27 
Bee ccchat \ 27 23. | 26 (or 27) } es 24 24 23-27 | 
Iai Po ppoeen 8 9 8 10 (or 9) 8 9 (or 8) 8-10 | 
SEOuAl semooonaus 3 3 3 3 3 3 3 | 
Sacro-caudal 8 9 9 (or 10) | 9 (or 10 3 ess 3-11 | 
or 11) | } 
Canales. citer ie, - 10 5 8 (or 9) 8 (or 9) 7 (or 9) 2 | 5-10 | 
Sacro-caudal and | 
caudal together. . 18 14 17 (or 19) | 18 (or 20) | 10 (or 12) ? | 10-20 
Abeigill “Sethe daca 56 49 54 55 (or 59) | 45 (or 47) ? 45-59 | 



CHARACTERS COMMON TO STRUTHIO AND RHEA. 
Axis vertebra with a hypapophysis, with or without well-developed hyperapophyses ; 
cervical vertebre greatly elongated; neural spines of cervical vertebra small or almost 
obsolete; catapophyses commencing about the sixth vertebra; catapophyses never 
forming a ring; diapophysial lamella extending towards posterior zygapophysis, small 
