216 - MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
The following pair (7th thoracic) are long, but without sternal segments; the 8th 
pair are short and fuse with the pre-ilium. 
In Rhea there are two free cervicals, three pairs of thoracic articulating with the 
sternum by sternal ribs, and provided with very long uncinates. ‘The 4th and oth 
pairs are long, but have no sternal segments. The 6th pair are very short and fuse 
with the pre-ilium. 
Amongst Dinornithide there appears to be some variation. 
In Dinornis maximus there are three free cervicals, two thoracic connected with the 
sternum by sternal segments, one long free rib, and three free ribs behind this 
overlapped by the pre-ilium. 
In Pachyornis there seems to have been but one free cervical or cervico-thoracic, 
three thoracic articulating with the sternum, four long free ribs, and short free ribs, 
these last two being overlapped by the ilium. The uncinates were very long. 
In Apteryx the ribs are remarkable for the great breadth and flatness of their 
vertebral segments. There may be one or two pairs of cervico-thoracic ; there are four 
thoracic articulating with the sternum (in a skeleton of A. australis I found five on 
one side, and in a skeleton of A. oweni, both in the Rothschild Coll., I found but 
three thoracic vertebra connected with the sternum) and four pairs of free ribs behind 
these, all of which are overlapped by the pre-ilium. The last pair are often 
exceedingly short. Six pairs of ribs bear uncinates, the series commencing in the 
last cervico-thoracic. The uncinates are long and broad, extending backwards to the 
hinder border of the rib next behind. 
In the ribs of all the Pulwognathe, save Apteryx and some Tinamous, there is a 
large pneumatic aperture lying in the cleft between the tuberculum and capitulum. 
THe STERNUM AND PEcTORAL ARCH. 
a. The Sternum. 
As with the other portions of the skeleton so far examined, so with the sternum, 
Dromeus possesses the most generalized type. 
The sternum of the young Dromeus and that of the young Caswarius are very 
similar in appearance ; in the adult they are readily distinguishable. 
In the adult Dromeus the anterior lateral processes are very long, slender, and 
directed upwards and backwards. There is no spina externa nor interna, but a deep 
emargination in their place. The ventral lips of the coracoid grooves are well 
developed. ‘The articular surfaces for. the coracoids are short, not exceeding in 
length the distance between the articulation for the first and third sternal ribs. 
These grooves differ from those of all the other Palwognathe in that they overlap, 
causing the bases of the coracoids to cross one another in the middle line as in many 
Carinae. 
