Classification of the Animal Kingdom, 29 



from each other in some trivial circumstance, while those of each group 

 agree in all theii* general structure. The specific name is the lowest term to 

 which we descend, if We except certain peculiarities, generally induced by 

 some modification of native habits, such as are seen in domestic animals. — 

 These are called varieties, and seldom endure bevond the cause which occa- 

 sion them. 



Several genera which have certain traits in common are combined to 

 form a family. Thus, the alewives, herrings, shad, &c., form a family called 

 CLUPEiDiE, among fishes ; the crows, black-birds, jays, &c., form the family 

 CoRviD^, among birds. Families are combined to form orders, and orders 

 form classes, and finally, classes are combined to form the four primary 

 divisions of the animal kingdom, namely, the departments. 



For each of these groups, whether larger or smaller, we involuntarily 

 picture in our minds an image, made up of the traits which characterize the 

 group. This ideal image is called a type, a term which there will be fre- 

 quent occasion to employ, in our general remarks on the animal kingdom. — ■ 

 This image may correspond to some one member of the group ; but it is 

 rare that any one species embodies all our ideas of the class, family, or genus 

 to which it belongs. Thus, we have a general idea of a bird ; but this idea 

 does not correspond to any particular bird, or any particular character of a 

 bird. It is not precisely an ostrich, an owl, a hen, or a sparrow ; it is not 

 because it has wings, or feathers, or two legs ; or because it has the power 

 of flight, or builds nests. Any, or all of these characters would not fully 

 represent our idea of a bird ; and yet every one has a distinct ideal notion of 

 a bird, a fish, a quadruped, &c. It is common, however, to speak of the 

 animal which embodies most fully the characters of a group, as the type of 

 that group. Thus, we might perhaps regard an eagle as the type of a bird, 

 the duck as the type of a swimming-bird, and the mallard as the typQ of ii 

 duck." 



The following is the sketch of the classification of the animal kingdom 



given in the work from which the above is quoted, — this system differs in 



some respect from those in general use at present. We shall point out some 



of those differences hereafter : — 



The Animal Kingdom consists of four great divisions which we call 

 Departments, namely, 



I. The department of Vertebrata. 

 II. The department of Articulata. 

 III. The department of Mollusca. 

 TV. The department of Eadiata. 



I. The department of Vertebrata includes all animals which have an 

 internal skeleton, with a back-bone for its axis. It is divided into four 



1. Mammals (animals which nurse their youner). 



2. Birds. ^ 



3. Reptiles. 



4. Fishes. 



The class of Mammals is subdivided into three orders. 

 a. Beasts of prey {Carnivora). 



