EOCENE ARTIODACTVLES 333 



These general characters only just serve to differentiate the 

 family ; but they illustrate its archaic character, in which it 

 resembles the Xiphodontidae, and even more the Anthraco- 

 theriidae. A survey of some of the genera which have been 

 assigned to the family will bring out other features in the 

 organisation of these very ancient Artiodactyles. 



Anoplothermm is so called on account of the fact that it is, 

 like all ancient Artiodactyles, without horns or claws. Tusks it 

 might have, but as a matter of fact has not. There are, as in 

 Artiodactyles generally, nineteen dorso-lumbar vertebrae ; the 

 long tail has numerous chevrons. The shoulder blade has a well- 

 marked acromion and a distinct coracoid process ; it is wide 

 proximally. The bones of the fore-arm and fore-leg are, as is 

 usual in primitive Artiodactyles, separate. 



In the skull the chief features, in addition to that mentioned 

 in the definition of the family, are the large size of the par- 

 occipital processes ; there is no fossa lachrymalis or deficiency in 

 the side of the face. The animal is three-toed, both in the fore- 

 and hind-limbs. The second toe is nearly as large as the Artio- 

 dactyle third and fourth. There are tiny rudiments of the two 

 remaining fingers. The hind-foot is also three- toed, and there is 

 a trace of the hallux. The fingers are so widely separated and 

 divergent from each other that it has been suggested that the 

 animal had webbed feet and inhabited marshes, in which it swam 

 by the aid of its long tail. The creature was the size of a Tapir. 



Closely resembling Anoplotherium are a number of other genera. 



Biplolune ( = Hyracodontotherium) was much like the last, 

 but was a more delicately-formed animal. The fingers and toes 

 (three of each) end in such sharply-pointed phalanges that claws 

 seem to be almost suggested. There are several species of this 

 genus. Bacrytherium differs by the presence of a lachrymal fossa. 



JDicliolune has four-toed extremities, of which the lateral ones 

 are more slender and shorter than the two middle ones. As in 

 other Anoplotheriidae, the anterior premolars are furnished with 

 a sharp cutting edge. 



Order V. SIRENIA. 



Aquatic Mammalia, with but few scattered hairs ; hind-limbs 

 absent; fore-limbs paddle-shaped ; tail iiattened, and either Whale- 



