362 Transactions of the South African Philosophical Society. 



overlaps the fibulare so as to almost completely hide it. The fibulare, 

 though in the same relative position to the fibula and of the same 

 shape as in the earlier stage, is relatively much smaller. The inter- 

 medium is still a distinct element, but is shifted a little more upwards 

 towards the distal end of the tibia. The distal tarsal elements are 

 not very distinct, but are probably second, third, and fourth tarsalia. 

 The second, third, and fourth metatarsals are all well developed and 

 chondrified. The first metatarsal is only partly chondrified at its 

 distal end. The fifth metatarsal is quite small. Phalanges are well 

 developed on the third and fourth toes, and a small phalanx is on 

 the second toe. 



There are a number of interesting points in connection with the 

 development of the foot. In the first place it is interesting to note 

 that the embryo ostrich has five toes more or less developed, and the 

 three centre ones fairly well developed. We are probably justified 

 in inferring that the immediate ancestor of the ostrich had three 

 functional toes, and possibly that the more remote ancestor had a 

 functional hallux. The 10-day embryo with its fifth metatarsal 

 larger than the first suggests a more remote ancestor with all five 

 digits functional, and possibly the outer four used for walking. The 

 large size and early development of the fibulare suggests a well- 

 developed outer side of the pes in a remote ancestor. And it is 

 curious to note that in the manus there is similar evidence of an 

 early greater development of the outer side. Another point of 

 interest is the evidence that the ascending process of the astragalus 

 is a true intermedium. This is confirmatory of the evidence 

 obtained in various sea-birds by Morse, and in agreement with the 

 opinion held by Kitchen Parker, Seeley, and others, though Jeffery 

 Parker was unable to find any evidence of a distinct intermedium in 

 Apteryx, and considers that the ascending process is a development 

 of the tibiale. 



The Oeigin of Bibds. 



The origin of birds, like that of mammals, has for many years 

 given rise to much discussion. But though a number of different 

 views have been held, they have never differed from each other so 

 widely as have the views concerning the origin of mammals. Gegen- 

 baur, Huxley, and Cope, from their study of the anatomy of the 

 dinosaurs, came to the conclusion that these extinct reptiles are 

 intermediate in many points of structure between typical reptiles, 

 such as the crocodile, and birds ; and for some time it was pretty 

 generally held that the ancestors of the birds were to be found 

 among the dinosaurs. When, however, the dinosaurs became 



