Relation of Higher Animals to Man 559 



We have here then three diverging hnes of placental mam- 

 mals, that might be compared in some of their genera from the 

 standpoint of mental evolution in relation to the utilization of 

 appendages as conductors or originators of stimuli. Many of 

 the Rodentia are purely cursorial animals, and receive environal 

 stimuli from without only by the eyes, nose, ears, or skin. But 

 in the squirrels, marmots, and others frequent use is made of 

 the forelimbs for climbing, prehension, holding, and scooping. 

 These are amongst the most alert, active, and mentally highly 

 evolved of the group. But even they are excelled by the 

 beaver that utilizes forelimbs and teeth as accessory structures 

 for environal contact. The discernment and capacity for 

 gnawing trees into suitable length, for guiding them in the 

 water, for hauling them to their settlements, for rearing lake 

 dwellings therefrom, for placing, plastering, and uniting them 

 in so doing, for cooperating with each other in the common 

 colonial work, and for defending the whole, indicate at once the 

 passage inward to the brain of many and varied stimuli, as 

 well as efferent impulses correlated with these. The beaver, 

 therefore, exhibits a surprisingly high cognitic as well as cogitic 

 capacity, the latter having enabled the group to elaborate and 

 adopt a fairly perfect system of colonial or social living. Mor- 

 gan's apparently exhaustive description suggests that more ex- 

 tensive observations and especially experiments might yield an 

 added harvest of results. 



Now the beaver is allied to the rabbit, guinea-pig, and other 

 familiar rodents, that display an intelligence little if at all higher 

 than that of the most simple mammal. But a very fair index 

 is got to their relative mental development, if we note the 

 degree to which the forelimbs are used for ])rogression only, or 

 for added and more diversified environal acts. So, while the 

 guinea-pig, the rabbit, the capybara, the sc^uirrel, the marmot, 

 and the beaver show close anatomical affinity, in active cogitic 

 response they possess an increasing intelligence in the order 

 given, to a degree that raises the last greatly above the first. 



The remarks of Romanes therefore are so far true {50: 35.'J): 

 "In no other group of animals do we meet with nearly so strik- 



