HISTORY OF THE JTOXODONTIA 465 



very heavy, the bones very massive and with large projections 

 for muscular attachments. The fore leg was much shorter 

 than the hind, depressing the neck and head in very curious 

 fashion. The shoulder-blade was rather narrow, the spine 

 without acromion or distinct metacromion; the hip-bones 

 were greatly expanded and turned outward, quite in elephant- 

 hke fashion-, a character which almost invariably accompanies 

 great increase in bodily mass. The thigh-bone was also very 

 elephantine in appearance, a likeness due to its shape and pro- 

 portions, to the loss of the third trochanter and the flattening 

 of the shaft, so that the width much exceeded the antero- 

 posterior thickness. All of these characters are, as a rule, asso- 

 ciated with greatly augmented weight and have been independ- 

 ently acquired in several series of large and massive animals, 

 elephants, fuintatheres, ftitanotheres, and to this list should be 

 added the ftoxodonts. In the fore-arm the bones were sep- 

 arate and the ulna was quite unreduced and very stout, but in 

 the lower leg, which was very short in comparison with the 

 thigh, the tibia and fibula were coossified at the upper end, 

 but not at the lower, a most exceptional arrangement. The 

 feet were surprisingly small and had but three digits, the reduc- 

 tion from the original five having proceeded to that extent 

 before the process was arrested by augmenting weight. The 

 heel-bone (calcaneum) was so articulated with the other bones 

 of the tarsus as to project almost straight backward, nearly 

 at a right angle to the position normal in a digitigrade foot, 

 a feature which is not known to occur in any other mammal. 

 The hoof-bones were so small and nodular that the foot must 

 have been of the columnar type, the weight resting upon the 

 usual elastic pad. 



The restoration (Fig. 121, p. 217) shows ^Toxodon as a very 

 heavy, slow-moving, water-loving animal ; the aquatic habits 

 are, of course, conjectural, but the general proportions are 

 accurately given by the skeleton. 



From the Pleistocene, \Toxodon may be followed back 



2h 



