ORDERS, FAMILIES, V 



types or plans, seemingly an abstract induction of ours, are as real as the 

 birds themselves. It is natural then to divide birds into three primary 

 groups: Aerial Birds (Aves Aerece), Terrestrial Birds (Aves Terrestres) 

 and Aquatic Birds {Aves Aquaticce). An illustration will make this clear. 

 Men build machines to transport themselves and their goods ; the only 

 known media of transportation are the air, the earth and the water ; and 

 we do not imagine any sort of vehicles more nnliko than a balloon, a 

 buggy, and a brig; these, therefore, exemplify the most fundamental division 

 of machines for transportation. 



§ 18. Orders. Taking any one of these types of structure, we find that 

 it may be unfolded, or carried out, in difierent ways. Studying all known 

 aquatic birds, for exami^le, we see that their plan of life is fulfilled iu four 

 different ways ; it is exhibited under four aspects, or modes of execution, 

 each distinguished by some particular combination of aquatic characters 

 with certain other characters that we did not take into account in framing 

 our Aves Aquaticce. Thus a goose, a gannet, a gull and a guillemot, all 

 agree iu aquatic characters, but differ from each other by each having certain 

 characters that the other three lack. Characters markiuo: such modes of ex- 

 hibition are called ordinal; and the groups so organized. Orders. In our 

 illustration, there are likewise four plans of aquatic machines ; diving bells, 

 sailing vessels, steamships and rowboats, clearly distinguished by the way 

 in which motion (the prime function of all vehicles) is effected ; in this case 

 it is by weight, by wind, by steam, by muscle ; therefore the machinery by 

 which these forces are applied, furnishes ordinal characters of aquatic 

 vehicles. 



§ 19. Families. But all the birds of an order are not alike; some re- 

 semble each other more than they do the rest ; so another set of groups 

 must be made. These groups are called Families; they consist in a certain 

 combination of all ordinal characters with special sets of characters of the 

 next lower grade or value. Let x represent the sum total of strictly ordi- 

 nal characters, and suppose, we find these variously combined with a certain 

 number of the next lower grade of characters, as a, b, — -f for instance ; then 

 the particular combination x (abc) is one family ; x (bef) another ; x (cde) 

 another, etc., and we shall have as many families under an order as there 

 actually are such combinations. Sometimes an order may be represented 

 by X (a. . . f) ; then there is but one family, as, for example, in the aquatic 

 order Lamellirosires where the Anatidm alone furnish every one of the ordi- 

 nal features, and are equivalent to the order; that is to say (a . . ._/) = x, 

 because no character from a to y is wanting in any member of the order. 

 In our order sailing vessels, of aquatic machines, masts and sails are ordi- 

 nal characters, because they are essential apparatus to catch the wind. 

 But these may be of a varying number, etc., upon which we might found 

 families of sailing-vessels, as the ship family, represented by x (three masts 

 -\- square sails) ; the schooner fiunily x (two masts -f- fore-and-aft sails) ; the 

 sloop family x (one mast -\- fore-and-aft sails), etc. Diving bells, I sup- 



KEY TO N. A. BniDS. 2 



