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above described, and which are peculiar among known Mammalia to the 

 present genus. The palatal surface of the maxillary bones is obliquely- 

 perforated by two large foramina, from which two deep longitudinal 

 grooves extend forwards and are gradually lost ; we find the posterior pala- 

 tine foramina represented by similar grooves and foramina in theCapybara. 



The intermaxillary bones, though large, are relatively of less extent 

 than in the Rodents generally. The nasal processes do not reach the 

 frontal bone, but are limited to the anterior half of the nasal boundary ; 

 approaching in this respect to the Herbivorous Cetacea. In the outward 

 expansion of their anterior extremities, the intermaxillaries resemble 

 those of the Hippopotamus, in which however this character is more 

 strongly marked. The intermaxillaries in the Hippopotamus are also 

 much less firmly united to the maxillary bones than in the Toxodon, 

 and are consequently commonly lost in the fossil crania. On the palatal 

 surface of the intermaxillary bones there are two grooves which diverge 

 forwards from the line of the suture ; and anteriorly to these grooves 

 there are the two large anterior palatine foramina. The maxillo-inter- 

 maxillary sutures on the palate converge as they extend backwards to a 

 point ; there appears to have been a fissure left between this suture and 

 the mesial suture of the intermaxillaries ; in which structure the Toxodon 

 resembles the Hippopotamus. 



The sum of the different affinities, or indications of affinity, which are 

 deducible from the cranium of this most curious and interesting fossil 

 mammal, establishes the conclusion that the Toxodon is referrible to the 

 order Pachydermata. But the structure, form and kind of teeth in the 

 upper jaw, show that the gigantic Toxodon was intimately related to the 

 Rodent order. From the characters of this order, as afforded by the 

 existing species, the Toxodon, however, differs in the relative position 

 of the supernumerary incisors, and in the number and direction of the 

 curvature of the molars. 



The Toxodon again differs from the true Rodents, and resembles the 

 Wombat and the Pachyderms in the transverse direction of the articular 

 cavity of the lower jaw. 



It deviates from the Rodentia and approximates to the Pachydermata 



