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Dr. W. Kowalevsky on the 



[Feb. 6, 



toothed Paridigitata, following the adaptive mode of reduction ; but as it 

 was reached by the same group on the madaptive mode (Entelodori), and 

 as the parallel group of crescent-toothed Paridigitata, whose reduction is 

 going at a quicker rate, has already reached it, there can be no doubt 

 that the Suina are tending also to the same culminating point. In 

 reaching it the lateral digits will be entirely lost, the trapezium will 

 coalesce with the magnum, and the second cuneiform with the third; 

 the middle metacarpals and metatarsals will coalesce into a complete 

 cannonbone, and probably the stomach will become still more compli- 

 cated, and they will ruminate. That this state is the goal towards 

 which the Suina tend I have little doubt ; but it is more than probable 

 that man by his influence will prevent them from ever reaching it. 



Our task is more difficult when we come to inquire into the line of de- 

 scent which has given rise to the Ruminantia. As stated before, I cannot 

 put the Anoplotherium, nor the Xiphodon, in their pedigree. In my 

 opinion, the line which ends in Ruminantia branched off from the small 

 tetradactyle Hyopotamidce, which were so numerous in the Eocene period. 

 I find in the Eocene of Mauremont all stages of transition between the 

 five-lobed upper molars of these Hyopotamidae and teeth having a true 

 ruminant four-lobed pattern; these last have belonged to some small 

 species of Dichodon. Unfortunately we have no clue to the skeleton, 

 though, seeing the tetradactyle living Hyomoschus, it may fairly be 

 assumed that these early progenitors of Ruminantia were also tetra- 

 dactyle. The small tetradactyle Cainotherium is a very tempting genus 

 in speculations about the descent of Euminantia ; but I must exclude it 

 for many reasons, though I cannot here give them in full. Some of 

 these are as follows : — the Cainotherium retained till the Middle Miocene 

 five-lobed teeth on the Dichobune pattern (with the three lobes on the 

 posterior half of the tooth), while we have truly ruminant teeth already 

 in the Eocene ; it retained its upper incisors and free metatarsals, while 

 the much older Gelacus, Aym., which is already a true ruminant, had no 

 upper incisors and the metapodials were confluent in the adult. Caino- 

 therium seems to be a direct descendant of Dichobune, and to have become 

 extinct, without leaving any successors. 



Supposing that the Dichodon had a foot true to the tetradactyle type, 

 we do not find the earliest stages of reduction ; they were passed rapidly, 

 and in very ancient times : but there can be little doubt that the 

 Ruminantia began with a tetradactyle foot, and ended by a cannonbone 

 adapted to the whole distal surface of the carpus and tarsus. Such 

 adaptation of the two middle digits could not be obtained at one leap ; 

 and certainly all stages between a tetradactyle foot (in which every digit 

 was supported by a separate bone in the carpus and tarsus) and a 

 didactyle foot (in which the two enlarged middle digits have taken the 

 whole distal surface of all the carpal and tarsal bones) were passed by 

 this group in the same manner we have seen it in the Suina, but only a 



