44 



ORNITHOLOGY 



must have had a common ancestor nearer to them than is 

 the ancestor of any Carinate form seems to need no proof. 

 If we add to these the JSpyornis of Madagascar, the Eoi si] 

 Ratitx of the Siwalik rocks, 1 and the as yet but partially 

 recognized Struthiolithus of Southern Russia, 2 to say no- 

 thing of Gastornis, the evidence is stronger still Scattered 

 as these Birds have been or are throughout the world, it 

 seems justifiable to consider them the survivals of a very 

 ancient type, which has hardly undergone any essential 

 modification since the appearance of Bird-life upon the 

 earth — even though one at least of them has become very 

 highly specialized. 



No doubt the difficulty presented by the biconcave 

 vertebras of the earliest known representative of the 

 Carinate type is a considerable obstacle to the view just 

 taken. But in the American Journal of Science (April 

 1879), and again in his great work (pp. 180, 181), Prof. 

 Marsh has shewn that in the third cervical vertebra of 

 Ickthyornis "we catch nature in the act as it were" of 

 modifying one form of vertebra into another, for this single 

 vertebra in Ickthyornis is in vertical section " moderately 

 convex, while transversely it is strongly concave, thus 

 presenting a mar approach to the saddle-like articulation"; 

 and he proceeds to point out that this specialized feature 

 occurs at the first bend of the neck, and, greatly facilitating 

 motion in a vertical plane, is " mainly due originally to 

 its predominance." The form of the vertebra; would 

 accordingly seem to be as much correlated with the 

 mobility of the neck as is the form of the sternum with 

 the faculty of flight. If therefore the development of the 

 saddle shape be an indication of development, as well may 

 be the outgrowth of a keel. However, the solution of this 

 perplexing problem, if a solution be ever found, must 

 remain for future palasontological or embryological dis- 

 coverers. The present writer is far from attempting to 

 decide a question so complicated, though he does not 

 hesitate to say, notwithstanding the weight of authority 

 on the other side, that according to present evidence the 

 probability is in favour of the Carinate having been 

 evolved from a more ancient Ratite type. One thing 

 only is certain, and that is the independent and contempo- 

 raneous existence of each of these great divisions at the 

 earliest period when Birds at all like recent forms are 

 known to have lived. The facts that each of these types 

 was provided with teeth, and that the teeth were of a dif- 

 ferent pattern, are of comparatively secondary importance. 

 Tin- three It seems therefore quite justifiable to continue, after the 

 fashion that has been set, to separate the Class Aves into 

 three primary groups : — I. Sauritrx, II. Ratitx, III. 

 ( 'arinatx the earliest members of the two last, as well as 

 !v all of the first, being provided with teeth. These 

 three primary groups we may call " Subclasses." 3 Thus 



ill have : — 

 SAl'KUR/E, Hacked. An/imijiteryx the only known form. 

 BATIT.E, Menem, a. with teeth ; 



«.'. with biconcave vertebras — as 

 yet unknown; 



V . with saddle-shaped vertebras 

 — Hespi rornis. 

 b. without teeth — recent and existing 



forms. 



1 For notice of these see the papers by Mr Davies in the Geological 

 Magazbm . decade ii., vol. vii. p. IS), and Mr Lydekker in 



I ie A', ords of the Geological Survey of India (xii. p. 52). 



- Hi/I/. Acafl. So. St Petersburg, xviii. i>. 158; Ibis, 1874, p. 4. 



3 Prof. Huxley has termed them "Orders"; but ii is more in 

 accordance with the practice of ornithological writers to raise them to 

 a higher rank, and to call tin' secondary groups "Orders." There is 

 di il I" I"' ■'-aid in behalf of either view; but, as in most cases 

 the matter is not worth wasting words over it, 

 so long as we bear in mind that what here is meant by an " Order " of 

 Aves is a very different thing from an " Order " of ReptUia. 



So I, 



cla 



CARINA TiE, Merrem. a. with teeth ; 



a', with biconcave vertebras 



— Ickthyornis; 

 U. with saddle-shaped verte- 

 brae — as yet unknown. 

 b. without teeth — recent and 

 existing forms. 



We have now to consider the recent and existing forms 

 of toothless Ratitx. These were shewn beyond doubt by 

 Prof. Huxley to form five separate groups, which we shall 

 here dignify by the name of Orders, 4 adding to them a 

 sixth, though little is as yet known of its characteristics. 

 Of this, which contains the great extinct Birds of Mada- 

 gascar, he did not take cognizance, as it is here necessary 

 to do. In the absence of any certain means of arranging 

 all of these orders according to their affinities, it will be 

 best to place their names alphabetically, thus : — 



./Epyoknithes. Fam. jJSpyornithidx. 



Aptekyges. Fam. Apterygidx (Kiwi, vol. xiv. p. 104). 



Immanes. Fam. i. Dinornithidx ; Fam. ii. 1'ala- 

 l>li rygidx. b 



Megistanes. Fam. i. Casuariidx ; Fam. ii. Dromxidx 

 (Emeu, vol. viii. p. 171). 



Rhe.e. Fam. Rkeidx (Rhea, </■>'.)■ 



Struthiones. Fam. Strutkionidx (Ostrich, p. 62 

 infra). 



Some systematists think there can be little question of 

 the Struthiones being the most specialized and therefore 

 probably the highest type of these Orders, and the present 

 writer is rather inclined to agree with them. Nevertheless 

 the formation of the bill in the Apteryges is quite unique 

 in the whole Class, and indicates therefore an extraordinary 

 amount of specialization. Their functionless wings, how- 

 ever, point to their being a degraded form, though in this 

 matter they are not much worse than the Megistanes, and 

 are far above the Immanes — some of which at least appear 

 to have been absolutely wingless, and were thus the only 

 members of the Class possessing but a single pair of limbs. 



Turning then to the third Subclass, the Carinatx, then- 

 subdivision into Orders is attended with a considerable 

 amount of difficulty ; and still greater difficulty is presented 

 if we make any attempt to arrange these Orders so as in 

 some way or other to shew their respective relations — in 

 other words, their genealogy. In regard to the first of 

 these tasks, a few groups can no doubt be at once separated 

 without fear of going wrong. For instance, the Crypturi 

 or Tinamous, the Impennes or Penguins, the Striges or 

 Owls, the Psittaci or Parrots, and the Passeres, or at least 

 the Oscines, seem to stand as groups each quite by itself, 

 and, since none of them contains any hangers-on about the 

 character of which there can any longer be room to hesitate, 

 there can be little risk in setting them apart. Next comes 

 a category of groups in which differentiation appears not 

 to have been carried so far, and, though there may be as 

 little doubt as to the association in one Order of the 

 greater number of forms commonly assigned to each, yet 

 there are in every case more or fewer outliers that do not 

 well harmonize with the rest. Here we have such groups 

 as those called Pygopodes, Gavix, Limicolx, Galium, 

 Colwnbx, Anseres, Herodiones, Steganopodes, and Accipitres. 

 Finally there are two groups of types presenting character- 

 istics so diverse as to defy almost any definition, and, if it 

 were not almost nonsense to say so, agreeing in little more 

 than iu the differences. These two groups are those 

 known as Picarix and Alectorides ; but, while the majority 



Orders of 

 Ratitx. 



Orders of 

 Carinatx. 



4 See Ann. Nat. History, ser. 4, xx. pp. 499, 500. 



6 On the supposition that the opinions of Dr Von Haa !('/'. 

 Proc. .V. Zeal. Institute, vi. pp. 426, 427) can he substantiated ; but 

 they have since been disputed by Prof. Hutton {op. cit., ix. pp. 363- 

 365), and for the present it is advisable to suspend our judgment. 



