654 



SCIENCE PROGRESS 



One of the most important and elaborate palaeontological 

 memoirs published during the year is that by Mr. W. D. 

 Matthew on the Carnivora and Insectivora of the Bridger 

 Middle Eocene Basin, forming part 6 of the ninth volume 

 of the Memoirs of the American Museum of Natural History. 

 In a valuable review of the developmental history of the 

 Carnivora the author refers to an important cranial difference 

 between progressive and non-progressive types ; the cranial 

 region in the former being elongate, whereas in the latter it 



Fig. i. — Skull of Vulpavus profectus, an "adaptive" Creodont. Natural size. 

 From Matthew, Mem. Amer. Mus. Nat. Hist. 



is short. This may be illustrated by comparing the skull of 

 a primitive placental carnivore like Viverravus with that of 

 a carnivorous marsupial of similar size. In the placental there 

 is ample room for brain-expansion in both the longitudinal and 

 the transverse direction, without undue encroachment on other 

 parts and organs ; whereas in the short-skulled type brain- 

 growth is greatly hampered by the necessity of much rearrange- 

 ment of other parts of the skull and its organs in order to 

 provide sufficient space. 



