PHYLOGENY OF THE PAL.EOGNATH.E AND NEOGNATtLE. 235 



ulnare, and distal carpal mass, but also an intermedium, an element which has so far 

 been recorded previously in Opisthocomus and Dendroecia. 



The fact that in the adult Apteryx there is a distinct alar membrane, or patagium, 

 as has been pointed out by Parker, is strong evidence in favour of the view that the 

 wing of Apteryx is a degenerate structure, once capable of performing the duties of an 

 organ of flight. 



In JEpyornis, apparently the wing was represented only by the humerus. A humerus, 

 believed to be that of an JEpyornis, has been described by Andrews. Its length was 

 63 mm. The upper end resembled that of the humerus of Aptomis, the lower that of 

 Casuarius, " but still further reduced, the radial and ulnar trochleas uniting completely 

 to form a single articular surface." 



'6' 



The Pelvic Limb. 



The differences between the pelvic limbs of the existing Paheognathce are neither 

 many nor great. 



In Dromceus the femur differs from all the other Paheognathce, save Struthio, in 

 that it is highly pneumatic, and bears on the ventral aspect of the femur a large 

 pneumatic foramen. It lies between the great trochanter and the head of the femur. 

 The popliteal fossa is of moderate depth. 



The tibio-tarsus is not easily distinguishable from that of Casuarius. The chief 

 difference appears to rest in the slighter and less vertically extended procnemial crest. 

 This vertical direction is rather marked in Casuarius. The fibula extends to the lower 

 fourth of the shaft of the tibio-tarsus. 



The tarso-metatarsus is as long as the tibio-tarsus, grooved in front, and has a 

 moderately developed median keel to the hypotarsus. 



The proximal phalanx of digit II. is relatively long, the 2nd very short; in digit IV. 

 the proximal phalanx is long, the 2nd and especially the 3rd and 4th are very short. 



The pelvic limb of D. ater closely resembles that of D. novce-hollandice. The 

 anterior metatarsal groove is, however, somewhat deeper. 



The outer toe, in each foot, in this skeleton has lost one phalanx. 



In Casuarius the femur is non-pneumatic. The position of the pneumatic fossa in 

 Dromceus may be indicated by a minute aperture. The tibio-tarsus, as already pointed 

 out, differs but slightly from that of Dromceus. 



The tarso-metatarsus is much shorter than the tibio-tarsus, is very deeply grooved 

 anteriorly, and is pierced by a foramen dorsad of the scar for the tibialis antic us. 

 Thus it can readily be distinguished from the tarso-metatarsus of Dromceus. 



The ungual phalanx of the inner toe is greatly elongated ; in other respects the size 

 of the phalanges closely agrees with those of Dromceus, but the proximal phalanx of 

 digit II. is relatively shorter. 



