88 . DICTIONARY OF BIRDS 



the present to regard as a Subclass, separated into three Orders — Odontolcee, 

 Odontotormx and Saururse, — 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 unmistak- 

 ably points to a great antiquity for the Class. All are true Birds ; but 

 the Keptilian 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 Palseozoic rocks, or at least 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 Ratitse 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 rudi- 

 mentary 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 leaping 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 Archgeopteryx was on 

 the Carinate line cannot as yet be determined, and this is also to be said 

 of Ichthyornis ; but the biconcave vertebrae of the latter suggest its being 

 an early offshoot, while it is probable that Hesperornis came off from the 

 main " Struthious " stem and has left no descendants. 



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 eftorts at classification made by Sundevall have already several 

 times been mentioned, and a return to their consideration was promised. 

 In 1872 and 1873 he brought out at Stockholm a Methodi Naturalis 

 Avium Disponendarum Tentamen, two portions of which (those relating to 

 the Diurnal Birds-of-Prey and the " Gichlomorphee" or forms related to 

 the Thrushes) he found himself under the necessity of revising and modi- 

 fying in the course of 1874, in as many communications to the Swedish 

 Academy of Sciences (K. V.-Ak. Fdrhandl. 1874, No. 2, pp. 21-30 ; No. 

 3, pp. 27-30). This Tentamen, containing a complete method of classify- 

 ing Birds in general, naturally received much attention, the more so 

 l^erhaps, since, with its appendices, it was nearly the laft 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 arrange- 

 ment of the groups of Birds on their external features, he had hitherto 

 striyen to make his schemes harmonize if possible with the dictates of 

 internal structure as evinced by the science of anatomy, though he 



