PHTLOGEXT OF THE PAL.EOGNATH.E AND NEOGXATILE. 237 



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

 no conspicuous pneumatic foramina. The i^reat 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 /h'i»nn'/'s and Ca-snariiis. The popliteal fossa is well 

 defined, but not deep. 



The tibio-tarsus is much fiatteued from front to back, as in Aptevyx and j^pyornis ; 

 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 tlie genus. There is a strong extensor bridge and an 

 intercondylar tubercle. 



In jEpyoriii^ 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. 



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

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

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



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

 The ectotrochlea is widely se[)arated from the mesotrochlea. There is a low, median, 

 hypotarsal ridge. 



Phalanx 1 of digit li. is moderately long, tlie 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 Lromwiis. 



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

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

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

 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 epipliysis. Moreover, the resemblance to a true 



VOL. XV. — PART V. No. 17. — December, 1900. 2 l 



