lvon] the hares and their allies 347 



mandible 



The mandible of the Leporidae is characterized by the great de- 

 velopment of the angular process and of the condyloid process and 

 by the almost complete absence of the coronoid process. It does 

 not show very many variations, but there are a few which are con- 

 stant for some of the genera. 



In Lepiis and Oryctolagus the mandibles resemble one another 

 closely, and may be said to possess the typical form. 



In Pronolagns the angular process of the mandible is rather 

 straighter along the lower edge than it is in the mandible of the 

 Lepiis type. The mandible- of Caprolagus apparently resembles it. 



The mandible in Limnolagns has a very large, rounded, angular 

 process. The ascending ramus is rather wider than it is in the 

 genus Lcpus. The notch between the condyle and the angular 

 process is much smaller than it is in Lcpus. The condyle has a 

 greater antero-posterior dimension. 



The mandible of Nesolagus is similar, but the angular process 

 is smaller. 



The mandible of Syk-ilagiis very closely resembles that of Lcpus, 

 but the angular process is relatively larger, and the notch between 

 the condyle' and the angular process is shorter. In this respect it 

 resembles the mandible of Limnolagus. 



Brachylagus has a mandible resembling a small one of the Lepus 

 style, but the angular process is relatively as well as absolutely 

 smaller, and its edge is nearly straight. 



The mandible of Romcrolagus possesses wide ascending rami, 

 which are nearly vertical. The angle is well developed and its edge 

 moderately rounded. The notch between the ascending ramus and 

 the angular process is larger than it is in any of the other genera. 



The mandible of Pentalagns has a very large, rounded, angular 

 process, which is separated from the condyle by a small, shallow 

 notch. The antero-posterior dimension of the ascending ramus 

 and of the condyle is much greater relatively than it is in the other 

 Leporid.ie. It is an exaggeration of the mandible of Liinnolagus. 



OcnOTONID^ 



(Plate XC) 



The skull in the Ochotonidre is so entirely dififerent in form and 



structure from that of the Leporidas, that it is almost superfluous 



to point out difl:'erences. Tlie most conspicuous points in the skulls 



of the Ochotonidfe that serve to separate them from the Leporidae 



