518 



MR. W. K. PAEKEE ON THE OSTEOLOGY OF THE KAGU. 



and the shoulder-girdle of the Frog lie vei^ nearly on the same morphological level 

 (oj). cit. pis. 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 supiDlementary 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 con-elation 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 fonvards 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 do\\'nward 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 Avhich 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 (PI. XCI. fig. 1, and PI. XCII. figs. 9-11) are very 

 much like those of its immediate congeners the Psojihia, the Eurypyga, the Cranes, 

 and the Rails. The " os femoris " (PI. XCI. fig. 1,/, and PI. XCII. figs. 9, 9 «, 9 1) is 

 slender, more arcuate, and longer, relatively, than in Psophia and Eurypijga, and there- 

 fore more Ralline. A Table showing the comparative lengths of the femur, tibia, 

 tarsus, and middle toe will illustrate this : — 



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 Psopihia, Ocydronms, and 



