236 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 



In Struthio the femur, as in Dromceus, is highly pneumatic, and, as in Dromceus, 

 bears a large pneumatic fossa between the head of the femur and the great trochanter. 

 The shaft is relatively much thicker than in Dromceus or Cassowary, and the fibular 

 condyle is much larger than the inner tibial condyle. The groove dividing them is also 

 narrower and deeper than in Dromceus. 



The tibio-tarsus, apart from its greater size, is peculiar in the relatively smaller 

 size and hooked form of the ectocnemial crest, and the great length of the fibula, 

 which extends to within a short distance of the upper border of the proximal tarsal 

 mass. The extensor groove is shallow. Furthermore, the lateral borders of the 

 posterior trochlear surface are produced backwards and upwards into a pair of 

 proximal ridges at right angles to the long axis of the shaft. 



The tarso-metatarsus is of course at once distinguishable by the absence of ento- 

 trochlea. It is grooved anteriorly, and bears a pair of foramina dorsad of the scar for 

 the tibialis anticus. 



The ungual phalanx of the outer toe is represented by a small nodule. 



In Rhea the femur is non-pneumatic. It may be at once distinguished from that 

 of any other Palceognathce by the great depth of the popliteal fossa. 



The tarso-metatarsus resembles that of Struthio in the feeble development and in 

 the form of the ectocnemial crest and in the backward projection of the condyle of 

 its distal extremity. The femur falls far short of the level of the tarsal mass. The 

 tarso-metatarsus has a shallow groove anteriorly, a deep fossa above the scar for the 

 tibialis anticus, and a very broad and low intercotylar process. The hypotarsal keel 

 lies to the inner side of the median line. In Dromceus and Casuarius it is median in 

 position. 



The 1st phalanx of digit n. is conspicuously lengthened, the 2nd is very short ; 

 of the IV. digit the proximal phalanx is long, the 2-4 very short. 



In Apteryx the femur is relatively large and more slender than in any other living 

 Palceognathce, save the Tinamous. It is non-pneumatic, and the popliteal fossa is 

 deep. 



The tibio-tarsus proximally is broad and flattened from back to front, neither the 

 ecto- nor procnemial crests are much developed. The extensor groove is deep. The 

 intercondylar gorge is deep, and the ento-condyle of great size. 



The tarso-metatarsus is shorter than the femur, much flattened from back to front ; 

 the intercotylar tubercle is well marked ; there is a fossa above the scar for the tibialis 

 anticus ; the 2nd and 4th trochlea? are widely separated from the meso-trochlea. The 

 hypotarsus bears a pair of low median ridges. 



There are four digits. The digits contain no conspicuously shortened or elongated 

 phalanges, and therein differ from the other Palceognathce herein described. 



In Dinornis the femur is relatively much shorter and thicker than in Struthio. Its 

 distal end is of great width ; the intercondylar gorge is very wide and shallow and 



