INTRODUCTION 107 



or less accuracy in any text-book of zoology,^ and it is enough to remark 

 that by the naturalist just named Birds and Reptiles have been brigaded 

 together under the name of Sauropsida as forming one of the three 

 primary divisions of the Vertebrata — the other two being Ichthyojjsida and 

 Mammalia. Yet Birds have a right to be considered a Class, and as a 

 Class they have become so wholly differentiated from every other group 

 of the Animal Kingdom that, among recent and even the comparatively 

 few fossil forms known to us, there is not one about the assignation of 

 which any doubt ought now to exist, though some naturalists have 

 refused a place among Aves to Archseo2:iteryx, of which, as elsewhere stated 

 (pages 278-280), the remains of only two individuals — most probably 

 belonging to as many distinct forms ^ — have been discovered. Yet one of 

 them was referred, without much hesitation, by Vogt to the Class Eejptilia 

 on grounds which seem to be mistaken, since it was evidently in great 

 part if not entirely clothed with feathers,^ and scarcely any one now 

 doubts that its Bird-like characters predominate over those which are 

 obviously Reptilian, while most authorities leave the genus as the sole 

 representative as yet known of the Subclass Saurue^, established for its 

 reception by Prof. Hackel. The great use of the discovery of Archeeo2)teryx 

 to naturalists in general was the convincing testimony it afforded as to 

 what is well called "the imperfection of the Geological Record." To 

 ornithologists in particular its chief attraction is the evidence it furnishes 

 in proof of the evolution of Birds from Reptiles ; though, as to the group 

 of the latter from which the former may have sprung, it tells us little 

 that is not negative. It throws, for instance, the Pterodactyls * — so often 

 imagined to be nearly related to Birds, if not to be their direct ancestors 

 — completely out of the line of descent. Next to this its principal 



^ The various schemes for classifying Birds set forth by the autliors of general 

 text-books of Zoology do not call for auy particular review here, as almost without 

 exception they are so drawu up as to be rather of the nature of a compromise than 

 of a harmony. The best and most notable is that by Prof. Carus in 1868 {torn, 

 cit. i. pp. 191-368) ; but it is of course now antiquated. Among the worst 

 schemes is that by Prof. Glaus in 1882 (Ormidziige der Zoologie, ii. pp. 318-388) ; but 

 'Dv.'R.'B.%vivfig'sLehrbiK]iderZoologie[SQnsi,: 1892, pp. 538-544) is quite as bad. Of 

 most other similar text-books that have come under my notice, the less said the better. 



^ See Prof. Seeley's remarks on the differences between the two specimens (Geol. 

 Mag. 1881, p. 454). 



^ Vogt laid much stress on the absence of feathers from certain parts of the body 

 of the second example of A rcheeopteri/x now, thanks to Dr. Werner Siemens, in the 

 museum of Berlin. But Vogt himself shewed that the parts of the body devoid of 

 feathers are also devoid of skin. Now it is well known that among most existing 

 Birds the ordinary "contour-feathers" have their origin.no deeper than the skin, and 

 thus if that decayed and were washed away the feathers growing upon it would 

 equally be lost. This has evidently hajipened (to judge from photographs) to the 

 Berlin specimen just as to that which is in London. In each case, as Owen rightly 

 suggested of the latter, the remains exactly call to mind the very familiar relics of 

 Birds found on a seashore, exposed perhaps for weeks or even months to the wash of 

 the tides so as to lose all but the deeply-seated feathers, and iinally to be embedded 

 in the soft soil. Vogt's paper is in the Revue Scieyitijique, ser. 2, ix. p. 241, and an 

 English translation of it in The Ibis for 1880, p. 434. 



■* Inl^QQ Owen {Anatomy of Vertebrates, ii. p. 13) maintained that " Derivatively 

 the class of Birds is most closely connected with the Pterosaurian order," i.e. the 

 Pterodactyls ; and the view is probably still held by many persons. 



