An Introduction to Zoology. 23 



held in common with the beings around, and which are peculiar to the 

 individual. And the more numerous the surrounding beings, the more 

 numerous will be the traits which we must accumulate. So that if we 

 wished to distinguish one being from all the rest, it would be absolutely 

 necessary to give as his character a complete and laboured description of 

 him. 



Now it is obvious, that if animals were grouped according to the prin- 

 ciples above stated, that is, according to the similarity of their constitution, 

 this great inconvenience would be removed, since the name of the groupe 

 would at once convey to us all the qualities possessed by its members in 

 common, and the peculiarities of the individual, necessarily the smaller 

 portion, might in most cases be expressed in a few words. As this point 

 is of some importance, let us endeavour to illustrate it. Suppose we 

 wished to characterise any animal, say an Italian greyhound ; it is obvious 

 that a detailed description of his structure and habits Avould occupy many 

 pages. Now the requisite information is conveyed to any person, moderately 

 acquainted with the general classification of animals, in a few words : — we 

 say that the dog is an animal, of the division vertebrated, class mammalia, 

 order carnassiers, division carnivori^ tribe digitagrade, genus canis, species 

 canis familiaris, variety canis grajus, sub-variety canis Italicus. At each step 

 we reject a load of extraneous matter, and narrow considerably the limits 

 within which the animal is contained : ]. He is an animal ; this tells us 

 in one word that he digests, absorbs that which is digested, and is thereby 

 nourished. 2. He is vertebratedj that is, he has a back bone, an internal 

 skeleton, an alimentary canal, a circulating and respiratory apparatus, a 

 brain and nervous system, and the five organs of the senses. 3. He is of 

 the mammalia j that is, he is viviparous, and nourishes the young bv milk. 

 4. He is one of the carnassiers, or feeders upon animal substance generally; 

 lie lias therefore teeth of three kinds, two anterior extremities unprovided 

 with hands, a separate or opposeable digit or thumb, breasts variable in num- 

 ber, a single stomach, a short alimentary canal. 5. He is carnivorous, or a 

 feeder upon flesh; he has therefore six incisor teeth in each jaw, powerful 

 canine, and cutting molars, sometimes tuberculated, but never crowned with 

 angular projections or points. C. He is digitigrade, or walks upon the points 

 of his digits. 7. He is of the genus canis, and possesses therefore anterior 

 feet, with five digits; posterior, with claws not retractile; tongue soft. 

 8. His species is canis familiaris, whose characteristics are a curved tail, a 

 snout more or less prolonged, and coat varying in the nature of its hair and 

 in its colour. 9. He is of the variety canis grajus, or greyhound, possessin<r 

 elongated snout, long and delicate legs, abdomen suddenly contracted, and 

 coat silky; and finally, he is of the subvaricty canis Italicus, or Italian 

 grcyiiound. 



Now a description, much fuller than the above, is expressed by the 

 naturalist in the single specification "canis grajus," which implies all the 



