Why Ave There No Upper Incisors in the Ruminantia ? 149 



able that the domestic sheep, having been confined to short past- 

 ure for a long series of generations, have lost, in length, a portion 

 of their tongues ? 



In the camels, including the lamas, there is a wide departure 

 from the typical ruminants. In fact anatomically, the camel fami- 

 ly show a marked affinity to the pachyderms. They stand on the 

 border line of the ruminants where they join the pachydermata, 

 possessing characteristics of each. Their lips are large and fleshy, 

 the upper one cleft. Their dentition is peculiar, the young pos- 

 sessing a full set of incisors in the upper jaw, which fall out as the 

 animal approaches maturity, save the two latter ones, which are 

 permanent. 



We have here perfect corresponding relations between the im- 

 perfect set of upper front-teeth and the partly prehensile tongue 

 which they possess. The lips and tongue are nearly equally use- 

 ful in seizing and conveying food to the mouth. 



On the lowest round looking up towards the ruminants, stand 

 the kangaroos. These herbivorous marsupials do chew the cud, 

 though imperfectly, as they possess saculated stomachs approach- 

 ing the multiple condition of the typical ruminants. It is inter- 

 esting to find that these wonderful animals, of a wonderful country, 

 do not possess a prehensile tongue, but have instead, a full, strong 

 set of incisors in the upper jaw. Here we have then, one of the 

 best proofs that the use of the tongue regulates the presence of 

 incisors. 



Insectivorous edentata, embracing the armadillos, and ant-eaters 

 of South America, and the Panoglins and Ard-vark of India and 

 Africa — in these quadrupeds, the tongue is long and cylindrical, 

 and is protruded directly forwards, so that front teeth in either 

 jaw, would interfere with the necessary rapid motions of the 

 tongue in feeding. Hence, the total absence of front teeth in 

 either jaw, and in fact the ant-eaters have no teeth whatever, 

 being strictly edentate. These animals furnish us with another 

 proof that prehensile tongues are antagonistic to front teeth. 



If a prehensile tongue be cylindrical, then we will have a total 

 absence of front teeth ; if flat and coiled upward in using, then 

 we will find incisors only in the under jaw. 



