578 SCIENCE PROGRESS 



any other reptiles, is believed to have originated during the 

 Carboniferous in North America, whence it spread over the 

 world in the Permian. 



The opinion of Dr. Broom (referred to in my review for 

 1910) that primitive cotylosaurians and pelycosaurians originated 

 in South America and then spread in one direction to South 

 Africa and in the other to North America, is adversely 

 criticised, the author maintaining the view that the North 

 American representatives of these groups are autochthonous. 

 It is added that the smaller and less well-known cotylosaurians 

 will probably yield the connecting links between reptiles and 

 amphibians. 



In his table of classification Mr. Case includes in the family 

 Pariotichidce the genus Ectocynodon of Cope on the ground that 

 it differs from the typical Pariotickus by the sculptured roof of 

 the skull ; but Mr. E. P. Branson has shown (Journ. Geol. vol. 

 ix. pp. 135-9, pi. *•) tnat the supposed lack of sculpture in the 

 latter genus is due to the imperfection of the material on which 

 it was based. 



In a paper published in the Zoological Society's Proceedings 

 for 191 1 (pp. 893-925) Dr. R. Broom supplies additional evidence 

 of the resemblance between the skulls of the theromorphous or 

 anomodont (in the wider sense of that term) reptiles of South 

 Africa and those of mammals ; the carnivorous cynodont group 

 being the one in which the mammalian resemblances are most 

 conspicuous. " If the cynodonts," observes the author of this 

 paper, " are not nearly related to mammals, the group is still of 

 great interest as showing a marvellous parallelism with the 

 mammals in skull, teeth, girdles, limbs and digits ; but if, as all 

 recent work seems to indicate still more clearly, the mammalian 

 ancestor was probably a cynodont, the group becomes vested 

 with an interest altogether unique and everything bearing upon 

 it becomes worthy of the most careful study." 



Later on Dr. Broom, after referring to the fact that the Lower 

 Permian pelycosaurians of North America exhibit certain 

 mammalian features, remarks that these become more pro- 

 nounced in the therocephalians and typical anomodonts of the 

 Middle Permian of South Africa. " For the first time we get 

 a dentition clearly divided into incisors, canines and molars ; 

 for the first time we get a lower jaw with a dentary bone 

 which has a large coronoid process. We get a zygomatic arch 



