VERTEBRATE PALAEONTOLOGY IN 1910 667 



furnishes at least a conception of a primitive form ancestral to 

 cats and dogs." 



Later in his article Dr. Matthew replies to critics who have 

 doubted the theor}^ that the sabre-tooths attacked by dropping 

 the lower jaw into a nearly vertical position and stabbing with 

 the upper tusks. After supporting the theory by additional 

 evidence, he remarks that most of the early large ungulates 

 were of the " pachyderm " type, and thus fitted to receive this 

 method of attack, while they would not succumb to the mode 

 practised by lions and tigers. 



Finally, he observes that " with the rise and dominance 

 of the large light-limbed ruminants and horses, some of the 

 early sabre-tooths were correlatively adapted into the modern 

 type of felines, while as the surviving pachyderm phyla 

 became larger, thicker-skinned, and more powerful, the sabre- 

 tooths likewise became progressively larger, more powerful, 

 and developed heavier weapons to cope with and destroy 

 them. The final extinction of the machaerodont phylum was 

 probably largely conditioned by the growing scarcity and 

 limited geographic range of the great pachyderms." 



Dr. Matthew protests, however, against the idea that the 

 huge Pleistocene sabre-tooths died out as the result of over- 

 specialisation. 



Carnivora from, the Pliocene and Pleistocene of Mexico form 

 the subject of a paper by Dr. E. Freudenberg, published in 

 Geol. u. Pal. Abhand., ser. 2, vol. ix. pp. 195-231. The Pleistocene 

 forms appear identical with existing species, but a new Felis 

 and a new Hycenognathus are described from the Pliocene. 



In the above-mentioned article in the Memoirs of the Carnegie 

 Museum^ vol. iv. pp. 205-278, on the Miocene Carnivora of 

 Western Nebraska, Mr. Peterson, in addition to the description 

 of Daphcenodon and notes on its affinities, records a new genus 

 and species of the Amphicyoninoe, under the name of Borocyon 

 rohustum. This animal, which was of the approximate size of a 

 lion, appears to have been probably related to Daphcenodon^ but 

 with non-retractile claws. He likewise describes a new genus 

 and species of mustelines, Paroligobunis siniplicidcns. The 

 genus, which is evidently akin to Oligobunis^ of the John Day 

 formation, appears to have affinities to both otters and badgers, 

 and to be related to the European Miocene otter-like Potanio- 

 theriiun. 



