82 SCIENCE PROGRESS. 



of a small smooth brain and long face, are perhaps the (by 

 degradation) most aberrant members of their orders, rather 

 than the lowest, as has been on all hands hitherto assumed 

 — or, as Fiirbringer has aptly remarked of the Ratite Birds, 

 that they are " pseudo -primitive ". 55 



His arguments concerning the origin of the homodont 

 dentition, with numerical increase of teeth, by subdivision 

 of a less numerous heterodont one, appear well founded ; 

 but the assumption that the setting free of the fangs of 

 the tooth of a seemingly senile Seal, by a process of natural 

 wearing away of the crown, is indicative of the nature of 

 the activities originally at work in the evolution of the 

 Cetacea, is an absurdity ; and the argument that, because 

 evidence of the aforementioned subdivision is forthcoming 

 in the ontogenetic development of the latter order, the 

 converse holds good, that the heterodont teeth of their 

 ancestors must have arisen by fusion of simple conical 

 teeth of an approximately reptilian type, is illogical, if not 

 opposed to the known revelations of palaeontology. Inci- 

 dentally to this section of his work, the author reverts 

 to his investigations into the comparative odontology of 

 the Mammalia, and to his epoch-marking discovery that 

 the teeth of the polyprotodont marsupials are, with the 

 exception of the well-known successional pre-molar, all 

 of the first or milk series. It is not a little remarkable 

 that the subsequent investigations of Woodward, 56 while 

 confirming this deduction and showing that, in all probability, 

 the single successional tooth so called is, in the Macro- 

 podidae, but a displaced member of the common series, 

 variable in its secondary relationships with its fellows in 

 closely allied species, should leave it at present very 

 doubtful if the Diprotodont molars are not of the second 

 series. 



We welcome with satisfaction Kukenthal's discovery of 

 tegumental elevations, like those which in the land mammals 

 give rise to the pinna of the external ear ; but we cannot 

 accept his doubts concerning the real nature and morpho- 

 logical value of that structure originally described as a 

 vestigial pinna in the porpoise and white whale. 



