196 MAMMALIA. 



very often rudimentary. In both orders the tail varies from an extraordinary lengtli, 

 as in the squirrel and pheasant, to being very short, as in the hare and partridge. 

 No orders in their respective classes present the tail so spread out and flattened as 

 the Glires and Rasores — witness the beaver and peacock. In both orders the sense 

 of hearing is much developed. In both orders we find animals, such as squirrels 

 and pigeons, with their toes perfectly free; and others, as Hydromys and Phasianus, 

 which have them united at the base by a membrane. Castor is an aquatic animal, 

 having some relation to Cetacea; Struthio is a terrestrial animal, approacliing to 

 Notatores. And so on, relation comes so fast upon relation, that I know not how 

 we can for a moment hesitate to place the Glires opposite to the' Rasores. 



' I conceive it now to be demonstrated, that, so far as relates to the analogies ex- 

 isting in nature between the orders of Mammalia and Aves, we ought to place them 

 thus: — 



Animals typically. 



1. Fer^ carnivorous 1. Ratobes. 



2. Primates omnivorous 2. Insessores. 



.3. Glires frugivorous 3. Rasores. 



4. Ungulata frequenting the vicinity of water .... 4. Grallatores. 



5. Cetacea aquatic 5. Natatores. 



