556 



ORNITHOLOGY. 



Structure curved, usually very short, and always so concealed with- 

 ^— ~ ~v~~^in the body as not to be apparent as an external portion 

 of the limb. The next division is the leg or tibia (m), 

 frequently but erroneously called the thigh, probably 

 from its being the uppermost apparent portion. It is 

 usually covered with feathers, though sometimes bare on 

 its lower portion. Then follows the tarsus (n), that long, 

 slender, exposed portion, so conspicuous in almost all the 

 species, varying considerably among accipitrine birds, ra- 

 ther short in web-footed water-fowl, and greatly length- 

 ened in the majority of shore-birds or waders. Its upper 

 knobby portion, where it articulates with the tibia, is the 

 true heel, although generally in colloquial, and not sel- 

 dom in descriptive language, termed the knee. The pro- 

 minences of its lower extremity articulate with the toes. 

 The latter parts usually amount to four ; the hind toe, how- 

 ever, is wanting in many species, and the ostrich is general- 

 ly supposed to have only two toes, although Dr Riley has 

 demonstrated the existence in that bird also of a rudimen- 

 tary inner toe. The hind toe is by some regarded as the 

 first, the inner as the second, the middle as the third, and 

 the outer as the fourth toe ; and in this order there is a 

 progressive increase in the number of the joints of which 

 each is composed, — the first having two, the second three, 

 the third four, and the fourth five bones. The surface 

 of the tarsus, toes, and sometimes of the base of the tibia 

 when that part is exposed, is covered either with plated or 

 reticulated scales, of various forms in different species ; 

 and the tarsus is moreover often armed with one or more 

 spurs, — which, however, belong to the cutaneous rather 

 than the osseous system. A general notion of the latter, 

 as it exists in the class of birds, may be acquired by an 

 inspection of the skeleton of the golden eagle just referred 

 to (Plate CCCLXXXVII. fig. 3). We shall here add no- 

 thing more upon the subject. 



The position, and therefore to a certain extent the na- 

 ture, of many modern genera, of which we are unable 

 from want of space to give the characters, will be seen in. 

 the tabular views with which we terminate the present 

 treatise. A considerable discordance still prevails in re- 

 gard to the nature and amount of the generic groups in 

 Ornithology, — some writers advocating a numerous sub- 

 division, and consequent restriction, of characters ; while 

 others adhere, perhaps too tenaciously, to old associa- 

 tions, which naturally tend to the augmentation of spe- 

 cies, in other words, to the extension rather than the in- 

 crease of genera. The former plan is rendered neces- 

 sary to a great extent by the vast additions which have 

 been made to our knowledge of groups and of typical spe- 

 cies within the present century, and might be deemed 

 advisable among the larger genera even as a mere matter 

 of convenience ; — its abuse in the hands of unskilful or in- 

 experienced persons being of course no legitimate argu- 

 ment against it. There is, however, a great deal that is 

 arbitrary and unsettled in whatever principle may be sup- 

 posed to guide the modern naturalist in the formation of 

 his generic groups. The simplicity and ease of applica- 

 tion which characterised the former artificial systems have 

 been lost in their attempted demolition, while the recon- 

 structions now arising (in spite of the abundant though 

 not always acknowledged appropriation of some useful old 

 materials) are not yet so complete and commodious as to 

 afford the same accommodation to the benighted student. 

 Order will no doubt some day spring from chaos, and even 

 already, amid the darkness of the upheaving waters, are 

 many sunny spots of terra firma towards which we fondly 

 steer, " well pleased that now our sea should find a shore." 

 Naturalists, however, need by no means quarrel with each 

 other, as if there was a certain good to gain, or some great 

 physical truth to be established. " All the great business 



of genera and species," says Locke, " amounts to no more Genera. 



but this, that men make abstract ideas, and, setting them ' v— 



in their minds with names annexed to them, do thereby 

 enable themselves to consider things, and discourse of 

 them, as it were in bundles, for the easier and readier im- 

 provement and communication of their knowledge, which 

 would advance but slowly were their words and thoughts 

 confined only to particulars." " The reason," he says 

 again, " why I take so particular notice of this is, that we 

 may not be mistaken about genera and species, and their 

 essences, as if they were things regularly and constantly 

 made by nature, and had a real existence in things, — when 

 they appear upon a more wary survey to be nothing else 

 but an artifice of the understanding, for the easier signi- 

 fying such collections of ideas, as it should often have oc- 

 casion to communicate by one general term, under which 

 divers particulars, as far forth as they agreed to that ab- 

 stract idea, might be comprehended." 



The following observations by Mr Vigors may be intro- 

 duced with propriety in this place, as according closely 

 with our own views on the subject of generic divisions. 

 " But though nature nowhere exhibits an absolute divi- 

 sion between her various groups, she yet displays suffi- 

 ciently distinctive characters to enable us to arrange them 

 into conterminous assemblages, and to retain each assem- 

 blage, at least in idea, separate from the rest. It is not, 

 however, at the point of junction between it and its ad- 

 joining groups that I look for the distinctive character. 

 There, as M. Temminck justly observes, it is not to be 

 found. It is at that central point which is most remote 

 from the ideal point of junction on each side, and where 

 the characteristic peculiarities of the groups, gradually 

 unfolding themselves, appear in their full development; it 

 is at that spot, in short, where the typical character is 

 most conspicuous, that I fix my exclusive attention. Upon 

 these typical eminences I plant those banners of distinc- 

 tion, round which corresponding species may congregate 

 as they more or less approach the types of each. In 

 my pursuit of nature, I am accustomed to look upon the 

 great series in which her productions insensibly pass into 

 each other, with similar feelings to those with which I 

 contemplate some of those beautiful pieces of natural 

 scenery, where the grounds swell out in a diversified in- 

 terchange of valley and elevation. Here, although I can 

 detect no breach in that undulating outline over which the 

 eye delights to glide without interruption, I can still give 

 a separate existence in idea to every elevation before me, 

 and assign it a separate name. It is upon the points of 

 eminence in each that I fix my attention, and it is these 

 points I compare together, regardless, in my divisions, of 

 the lower grounds which imperceptibly meet at the base. 

 Thus also it is that I fix upon the typical eminences that 

 rise most conspicuously above that continued outline in 

 which nature disposes her living groups. These afford me 

 sufficient prominency of character for my ideal divisions ; 

 for ideal they must be, where nature shows none. And 

 thus it is that I can conceive my groups to be at once 

 separate and united ; separate at their typical elevations, 

 but united at their basal extremes. 



" It is difficult to convey, in terms sufficiently explicit, 

 an accurate definition of abstract notions like the present. 

 We may see the subject clearly ourselves, but not be able 

 to communicate it by words sufficiently intelligible, unless 

 to those who may happen to view it in the same light as 

 ourselves. I shall therefore take a familiar illustration, 

 which comes home to the feelings of every man, and where 

 it will be immediately apparent that strongly marked di- 

 visional groups may be kept apart from each other in our 

 conceptions, although we can recognise no absolute boun- 

 dary lines by which we can say they are separated. 



" Let us take, for instance, that period of time which in- 



