PHYLOGENT OF THE PAL.EOGNATHLE AND NEOGNATH^E. 237 



extends proximad on to the shaft, terminating rather behind its middle. There are 

 no conspicuous pneumatic foramina. The great trochanter is very large; it is pro- 

 duced upwards above the head, and not backwards caudad of the head, being an 

 exaggeration of what obtains in Dromwus and Casuarius. The popliteal fossa is well 

 defined, but not deep. 



The tibio-tarsus is much flattened from front to back, as in Apteryx and Mpyornis ; 

 the ectocnemial crest is large, and gives the anterior view of the proximal end of the 

 bone a flabellate form ; the procnemial crest is feebly developed. The shaft may or 

 may not be inflected —according to the genus. There is a strong extensor bridge and an 

 intercondylar tubercle. 



In JEpyomis the femur is also very short. The great trochanter is very lofty and 

 produced caudad. The intercondylar gorge is wide and deep, and the popliteal fossa 

 shallow. 



Tne tibio-tarsus has its proximal end much flattened from front to back; a feeble 

 procnemial and large laterally directed ectocnemial crest. Distally the shaft is 

 inflected. There is no extensor bridge, and the groove is shallow. 



The tarso-metatarsus is short, wide, and grooved anteriorly, but the groove is shallow. 

 The ectotrochlea is widely separated from the mesotrochlea. There is a low, median, 

 hypotarsal ridge. 



Phalanx 1 of digit II. is moderately long, the 2nd is short ; phalanges 2, 3 of 

 digit iv. are conspicuously short, the 4th is shorter. The proportions of the phalangeals 

 agree closely with those of Dromceus. 



In working out the development of Apteryx, Parker [71] found, in the earlier stages, 

 all five digits present — as in some Neognathce. The fifth digit was a short conical 

 cartilage attached by its proximal end to the fibulare, and by its pre-axial border to the 

 distale. 



The fibula was of the same length as the tibia. 



The tarsus contained the usual elements — a tibiale, fibulare, and distale. The 

 ascending process of the tibiale at no stage showed any sign of a separate origin, 

 comparable to an intermedium. Later, after hatching, there appears in the mesotarsal 

 articular pad a pair of centralia. Sometimes only one is present. 



The procnemial crest ossifies, as usual, from a separate centre. Concerning this 

 ossification I would remark that it is doubtful whether it has any phylogenetic signi- 

 ficance. Rather it would seem to be comparable to the separate ossification-centre of 

 the great trochanter of the mammalian femur, and to indicate a position of great 

 strain. In a recent paper I, however, described it as an epiphysis, as also, though 

 unknown to me at the time, did the late W. K. Parker [79]. In my own case I may 

 claim some justification, since the base of this procnemial ossification — that of a 

 young Grebe — was sufficiently large to form a complete tibial cap, divided from the 

 shaft by cartilage, as is a true epiphysis. Moreover, the resemblance to a true 



vol. xv. — part v. No. 17. — December, 1900. 2 l 



