192 



ON THE EXTINCT MAMMALIA OP 



Breadth of distal extremity, 



Greatest width of the ante-brachial articulation, 



Breadth of fore-arm bones together, at middle. 



Breadth of middle of radius. 



Breadth of middle of ulna, . 



Breadth of head of radius, . 



Circumference of femur 4* inches above distal end. 



Breadth at condyles of femur, 



Breadth of head of tibia, 



Breadth of distal end of tibia and fibula. 



Lines. 



22 

 17 

 15 

 10 

 7i 

 17 

 41 

 24 

 25 

 31 



Elotherium ingens. 



The fragments of teeth originally described under the name of Archceotheriiim ro- 

 bustum were supposed to indicate a different species from Elotherium Mortoni, on 

 account of their size exceeding that in the specimens referred at the same time to the 

 latter. The subsequent examination of additional specimens of E. Mortoni, from the 

 observed variability in size of corresponding parts of different individuals, have led 

 me to consider those referred to A. robusimn as belonging to larger individuals, per- 

 haps of the male, of the same animal. The collections of Dr. Hayden contain frag- 

 ments of jaws and teeth, found in association with the fossils of Elotherium Mortmii 

 in the Mauvaises Terres, which appear too large to belong to this species, even 

 making allowance for a considerable range in size. These I have referred to a differ- 

 ent species under the name heading the pi'eseut chapter, though I am prepared to 

 admit that these larger fossil remains may have pertained to robust males of 

 Elotherium Mortoni. Tlie species was about a third larger than E. Mortoni, and was 

 about the size of the Elotherium Ayrnardi of France. 



The specimens referable to Elotherium ingens are as follow : 



1. The fore i^art of the lower jaw, in advance of the second j)remolars. An 

 anterior view is represented, one-half the natural size, in figure 10, plate XXVII. 

 It contains the fangs of the first premolars, canines and incisors. It also contains 

 one of the mental protuberances nearly entire, and the greater part of the opposite 

 one. The measurements of the specimen are as follow : 



Inches. 



Height of symphysis, . . . . . . .4 



Breadth of jaw outside of canine alveoli, . . . . .31 



Breadth between ends of mental protuberances, . . - . .41 



Depth of jaw below first premolar, . . . . . .21 



