132 ORDERS BIMANA AND QUADRUMANA. 



I. BIMANA, or two-handed Mammals ; so termed from the 

 restriction of the thumbs or opposable fingers to the anterior 

 extremities only, which are employed for prehension^ whilst the 

 posterior are employed for locomotion. By this character, and 

 by his naturally erect position, Man is distinguished from all 

 other animals ; and consequently this order is composed of the 

 Human Races only. We shall presently see that, however 

 various the characters of different races, they are all entitled 

 to rank as belonging to the same species. The order Bimana is 

 further distinguished by the number and character of the teeth ; 

 there being 4 Incisors or cutting- teeth in each jaw ; Canine 

 teeth in each jaw, moderately developed ; and (in the adult, in 

 whom the last molars or wise teeth have been cut,) 5 Molar 

 teeth, having rounded or tuberculated summits, on each side of 

 each jaw. It is usual, in order to express briefly the number of 

 teeth in the jaws of an animal, to use the following method : 

 Those of the upper jaw are placed above a horizontal line, and 

 those of the lower jaw below it ; like the numerator and deno- 

 minator of a fraction ; thus, ^ would mean that there were 6 

 teeth of a particular kind in the upper jaw, and 4 in the lower. 

 The incisors, being all together in the centre, are specified by a 

 single number ; but the canines and molars, which are found on 

 either side, are expressed by two numbers, as thus 4 4, 

 meaning that there are 4 on each side. Hence the dental for- 

 mula, as it is termed, of Man, is as follows ; incisors J, canines 

 ^, molars JjJ. The value of such a short and simple expression 

 will hereafter become evident. 



II. QUADRUMANA, or four-handed Mammals, embracing the 

 Monkey tribe ; so termed from the possession of thumbs on all 

 the four extremities (in part of the group), thus giving to all of 

 them, in greater or less degree, the peculiar power of prehension 

 which this conformation imparts. But they are all, likewise, 

 concerned in locomotion also ; as the distinction between the 

 anterior and posterior extremities, which is so remarkable in 

 Man, does not here present itself, or is only seen in a slight 

 degree. The number of incisors is still , and of canines \ ; 

 but that of the molars is ^i, in a certain part of the group. 



