NATURAL SCIENCES OF PHILADELPHIA. 197 



By this means we should arrive at about a dozen orders of apparently the 

 same taxouomic value. 



With endless minor modifications at different hands, yet with main points 

 intact, this system has come into general use, holding its own against many 

 technical objections, with a vitality something remarliable in the history of 

 the science. There is that about it that appeals strongly to general opinion, 

 representing average " common sense," and commands assent, however quali- 

 fied and guarded. The most extensively used, it is also the best abused sys- 

 tem of all, particularly in that phase it gained at the hands of Swainson et aff. 

 Much argument, and not a little invective, has been wasted, or worse, upon 

 the various " quinary," " septenary," " circular," &c., systems that have re- 

 volved like satellites around Vigors' standpoint. It must be vital, or it would 

 before this have been buried. It must be weak at points, or it could not have 

 been so successfully attacked. It appears to have suffered more from the in- 

 discretion of its friends than the hostility of its enemies. 



The child's " classification " is the placing of objects in a line one after the 

 other. A step in advance is their arrangement in several contiguous lines, 

 straight or waved, parallel, oblique or crossing. The insurmountable difficulty 

 is that these lines lead anywhere, — nowhere in particular. Any linear arrange- 

 ment is so clearly impossible, that I only excuse myself for alluding to it at 

 all by taking it as the initial point of departure in this portion of the present 

 essay. It was a stride onward when the idea was conceived of making these 

 lines return upon themselves. Not only were otherwise inevitably bizarre 

 juxtapositions dene away with, but a greater end, the production of surfaces 

 instead of lines, was secured. Anywhere in these planes, from centre or type- 

 point to periphery or aberrant points, forms could be located. With the 

 " circle," an indefinite number of points of contact or inosculation became 

 possible. The circularian could bring his three, five, seven, or other " sub- 

 typipal" forms around his " type circle," weigh the importance of each by the 

 size of his circles, and grade relationships from near affinity to remote analogy. 

 The elastic sj-stem seemed perfect with its machinery of "wheels witliin wheels." 

 Criticism of this scheme has too often ended in a smile or a sneer, yet without 

 touching upon the really vulnerable pomt. A system that disposes objects in 

 circumscribed planes is a great advance over a linear arrangement, but it 

 stops half-way to the goal. The third dimension is needed ; to length and 

 breadth must be added thickness ; the circle must become a sphere. 



Thus I conceive that every group of birds, from the assemblage of indi- 

 viduals called a species, to the very highest, constitutes or represents a solid of 

 the three dimensions. We cannot predicate affinity or analogy only to the 

 right or left, — the top or bottom, — but must take it that all groups, near or 

 remote, may approach, touch, or fuse with each other, along the axis of either 

 of the thiee possible diameters. With whatever result in our attempt to pro- 

 ject an ornithological system on flat paper, yet we cannot imagine the groups 

 to be all distributed in one plane surface, or even in several " higher ' or 

 "lower" parallel planes. Just as the stars, that appear scattered on a con- 

 cave surface, are harmoniously distributed throughout space in its three ex- 

 tensions, so, types of birds with reference to each other. The avenues of 

 mutual approach, whatever their number, do not all lie in one plane, but may 

 lie in any of the perpendicular planes whose intersection generates a solid. 



I used the word " sphere " merely as the general expression of solids with 

 indefinite number of sides ; not presuming to say that this is the real shape 

 either of birds as a unit, or of their subdivisions. Birds could only assume 

 this shape if developed equally in all directions, which apparenllj', I may say 

 certainij^, is not the case. The figure may be conoidal, like half an hour-glass, 

 whose other half is reptiles, or only the Pterosaurian type of that class ; the 

 two meeting at a point, perhaps Archseoj^teryz. Speculations upon the contour 

 of the figure are, however, out of place. Again, the superficies of this solid, 

 whatever its form, is not necessarily, nor even probably, smooth. We may 



1869.] 



