Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/47

 specialized feature of teeth in distinct sockets. Hesperomis too, with its keelless sternum, had aborted wings but strong legs and feet adapted for swimming, while Ickthyomia had a keeled sternum and powerful wings, but diminutive legs and feet. These and other characters separate the two forms so widely as quite to justify the establishment of as many Orders for their reception, and the opposite nature of the evidence they afford illustrates one fundamental principle of evolution, namely, that an animal may attain to great development of one set of characters and at the same time retain other features of a low ancestral type. Prof. Marsh states that he had fully satisfied himself that Archseopteryx belonged to the Odontornithes, which he thought it advisable for the present to regard as a Subclass, separated into three Orders- Odontolcse, Odontotormse, and 8&amp;lt;nirur% all well marked, but evidently not of equal rank, the last being clearly much more widely distinguished from the first two than they are from one another. But that these three oldest-known forms of Birds should differ so greatly from each other unmistakably points to a great antiquity for the Class. All are true Birds ; but the Reptilian characters they possess converge towards a more generalized type. He then proceeds to treat of the characters which may be expected to have occurred in their common ancestor, whose remains may yet be hoped for from the Palaeozoic rocks if not from the Permian beds that in North America are so rich in the fossils of a terrestrial fauna. Birds, he believes, branched off by a single stem, which gradually lost its Reptilian as it assumed the Ornithic type ; and in the existing Ratitx we have the survivors of this direct line. The lineal descendants of this primal stock doubtless at an early time attained feathers and warm blood, but, in his opinion, never acquired the power of flight, which probably originated among the small arboreal forms of Reptilian Birds. In them even rudimentary feathers on the fore-limbs would be an advantage, as they would tend to lengthen a leap from branch to branch, or break the force of a fall in leap ing to the ground. As the feathers increased, the body would become warmer and the blood more active. With still more feathers would come increased power of flight as we see in the young Birds of to-day. A greater activity would result in a more perfect circulation. A true Bird would doubtless require warm blood, but would not necessarily be hot-blooded, like the Birds now living. Whether Archge.opte.ryx was on the true Carinate line can not as yet be determined, and this is also true of Ichthy- ornis ; but the biconcave vertebra; of the latter suggest its being an early offshoot, while it is probable that Hesperomis came off from the main &quot; Struthious &quot; stem and has left no descendants. Bold as are the speculations above summarized, there seems no reason to doubt the probability of their turning out to be, if not the exact truth, yet something very like it. From this bright vision of the poetic past a glimpse, some may call it, into the land of dreams we must relapse into a sober contemplation of the prosaic present a subject quite as difficult to understand. The former lunde- efforts at classification made by Sundevall have already all&amp;gt; several times been mentioned, and a return to their con sideration was promised. In 1872 and 1873 he brought out at Stockholm a Methodi Natumlis Avium Disponend- arum Tentamen, two portions of which (those relating to the Diurnal Birds-of-Prey and the &quot; Cichlomorphx,&quot; or forms related to the Thrushes) he found himself under the necessity of revising and modifying in the course of 1874, in as many communications to the Swedish Academy of Sciences (K, V.-Ak. Forhandlingar, 1874, No. 2, pp. 21-30; No. 3, pp. 27-30). This Tentamen, containing the latest complete method of classifying Birds in general, has naturally received much attention, the more so perhaps, since, with its appendices, it was nearly the last labour of its respected author, whose industrious life came to an end in the course of the following year. From what has before been said of his works it may have been gathered that, while professedly basing his systematic arrangement of the groups of Birds on their external features, he had hitherto striven to make his schemes harmonize if possible with the dictates of internal structure as evinced by the science of anatomy, though he uniformly and persistently protested against the inside being better than the outside. In thus acting he proved himself a true follower of his great countryman this respect, it must be said that when internal and exter nal characters appeared to be in conflict he gave, perhaps with unconscious bias, a preference to the latter, for he belonged to a school of zoologists whose natural instinct was to believe that such a conflict always existed. Hence his efforts, praiseworthy as they were from several points of view, and particularly so in regard to some details, failed to satisfy the philosophic taxonomer when generalizations and deeper principles were concerned, and in his practice in respect of certain technicalities of classification he was, in the eyes of the orthodox, a transgressor. Thus instead of contenting himself with terms that had met with pretty general approval, such as Class, Subclass, Order, Sub order, Family, Subfamily, and so on, he introduced into his final scheme other designations, &quot;Agmen,&quot; &quot; Cohors,&quot; &quot; Phalanx,&quot; and the like, which to the ordinary student of Ornithology convey an indefinite meaning, if any meaning at all. He also carried to a very extreme limit his views of nomenclature, which were certainly not in accordance with those held by most zoologists, though this is a matter so trifling as to need no details in illustration. It is by no means easy to set forth briefly, and at the same time intelligibly, to any but experts, the final scheme of Sunde vall, owing to the number of new names introduced by him, nevertheless the attempt must be made ; but it must be understood that in the following paradigm, in which his later modifications are incorporated, only the most remark able or best-known forms are cited as examples of his several groups, for to give the whole of them would, if any explanations were added, occupy far more space than the occasion seems to justify, and without such explanations the list would be of use only to experts, who would rather consult the original work. First, Sundevall would still make two grand divisions (&quot; Agmina &quot;) of Birds, even as had been done nearly forty years before; but, having found that the names, Altricesand Prsecoces, he had formerly used were not always applicable, or the groups thereby indicated naturally disposed, he at first distinguished them as Psilopsedes and Ptilopxdes. Then, seeing that the great similarity of these two words would produce confusion both in speaking and writing, he changed them (p. 158) into the equivalent Gymnopsedcs and Dasypszdes, according as the young were hatched naked or clothed. The Gymnopsedes are divided into two &quot; Orders&quot; seines and Volucres the former intended to be identical with the group of the same name established by older authors, and, in accordance with the observations of Keyserling and Blasius already mentioned, divided into two &quot; Series &quot;Laminiplantares, having the hinder part of the &quot;tarsus&quot; covered with two horny plates, and Scuttlh- plantares, in which the same part is scutellated. These Laminiplantares are composed of six Cohorts as follows : Cohors 1. CiMomorphie. Phalanx 1. Ocrcatse. 7 Families: the Nightingales standing first, and therefore at the head of all Birds, with the Redbreast, Redstart, and the American Blue-bird ; after them the Chats,
 * Linnaeus ; but, without disparagement of his efforts in