518 MR. W. K. PARKER ON THE OSTEOLOGY OF THE KAGU. 
and the shoulder-girdle of the Frog lie very nearly on the same morphological level 
(op. cit. pls. 6 & 7). 
With regard to the setting-on of the limb-girdle moieties, it will be seen that there 
is the greatest liberty with regard to the angle these plates form with the vertebral axis. 
As they are merely supplementary parts, and as they appear between the skin and the 
axial cartilages and muscles, there is nothing to prevent them shooting along the sub- 
cutaneous plane in any direction. In the Bird-class, where the skeleton is so marvellously 
modified in correlation with the functions and habits of a flying creature, the upper 
edge of the shoulder-girdle is directed very far backwards, the direction, from the narrow 
suprascapular top, being forwards and a little downwards to the glenoid region, and 
then suddenly downwards and backwards, the upper and lower halves lying at an acute 
angle. In the hip-girdle, on the contrary, the true apex is turned forwards, but runs 
also backwards by a very long upper margin, the general direction of the whole plate 
being backwards and a little downwards. The Kagu is peculiar among birds for a 
much more downward direction of the hip-girdle moiety than is common in its Class; 
but even in it there is but little approach to the condition of these parts in the 
Lacertian, where the ilium is set on to the spine at almost a right angle. 
With regard to the arrested metamorphosis of the hip-girdle in the Bird, it is worthy 
of remark that the pubis (the counterpart of the precoracoid bar which is the subject 
in the Bird and in the Mammal of such a large amount of morphological change) does 
die out at its anterior part in certain Raptores—for instance, the Falcons, Hawks, &c. 
The pubis, also, like the precoracoid, is the first to become enfeebled and modified, 
although in a less degree, 
The hinder limbs of the Kagu (Pl. XCI. fig. 1, and Pl. XCII. figs. 9-11) are very 
much like those of its immediate congeners the Psophia, the Ewrypyga, the Cranes, 
and the Rails. The “os femoris” (Pl. XCI. fig. 1, f, and Pl. XCII. figs. 9, 9a, 90) is 
slender, more arcuate, and longer, relatively, than in Psophia and Eurypyga, and there- 
fore more Ralline. A Table showing the comparative lengths of the femur, tibia, 
tarsus, and middle toe will illustrate this :— 
Femur. Tibia. | Tarsus. Middle toe. 
in. lin. in. lin, in. lin in. lin, 
Rhinochetus jubatus .......55- 2 7% 49 3 11 2 33 
Eurypyga helias 0.06... cece 1 43 3.0 2 1 1 4 
Psophia crepitans vo vvcvveveee 2 10 5 10 4 8 2 4 
Porphyrio poliocephalus........ 2 103 5 4 3.9 4 02 
Ocydromus australis .......4+. 3 24 4 63 ao} 2 64 
Here it is shown how extremely variable the relative proportions of these regions are 
even in birds so closely related as those given in the list. Altogether, the bones of 
the hinder limbs are much slenderer in the Kagu than in Psophia, Ocydromus, and 
