io6 DICTION AR Y OF BIRDS 



but a very little way in comparison with what we, or our successors, 

 may hope to reach in years to come. Still we may feel pretty confident 

 that we are on the right track, and, moreover, that here and there 

 we can plant our feet on firm ground, however uncertain, not to say 

 treacherous, may be the spaces that intervene. Now that geographical 

 exploration has left so small a portion of the earth's surface unvisited, 

 we cannot reasonably look for the encountering of new forms of extant 

 ornithic life that, by revealing hitherto unknown stepping stones, will 

 (j^uicken our course or effectively point out our path. Indeed, as a matter 

 of fact, the two most important and singular tyj)es of existing Birds — 

 Balxnicej)s and Rhinochetus — that in the latter half of this century rewarded 

 the exertions of travelling naturalists, have proved rather sources of per- 

 plexity than founts of inspiration. Should fortune favour ornithologists in 

 the discovery of fossil remains, they will unquestionably form the surest 

 guide to our faltering steps ; but experience forbids us to expect much 

 aid from this quarter, warmly as we may wish for it, and the pleasure 

 of any discovery of the kind would be enhanced equally by its rarity as 

 by its intrinsic worth. Even the startling revelation of the group named 

 Stereornithes has as yet done little except to add to our knowledge 

 a number of ancient types.^ However, it is now a well-accepted maxim in 

 Zoology that immature forms of the present repeat mature forms of the 

 past, and that, where Palaeontology fails to instruct us, Embryology may 

 be trusted to no small extent to supply the deficiency. Unhappily the 

 embryology of Birds has been till lately very insufficiently studied. We 

 liad indeed embryological memoirs of a high value, but almost all were 

 of a monographic character, and were only oases in a desert of ignorance. 

 The same may be said of MorjDhology, so that a really connected and 

 •continuous series of investigations, such as was instituted by Prof. 

 . Fiirbringer, marked a new starting-point ; for it seems clear that hence- 

 forth schemes for the Classification of Birds, as of other groups, will be 

 divided into those which are based on Morphology, and those which are 

 not — the latter falling year by year into disrepute. At the same time, 

 with the greatest resi^ect to Morphologists, it must be held that they, like 

 other men, are bound by the rules of evidence and the exercise of common 

 sense. Moreover, as the discrepancies between the schemes of diff'erent 

 Morphologists shew, individual opinion will have to be reckoned with for 

 some time to come. 



Birds are animals so similar to Reptiles in all the most essential 

 features of their organization that they may be said to be merely an 

 extremely modified and aberrant Reptilian type. These are almost the 

 very words of Huxley in 1866,^ and there are now but few zoologists 

 to dissent from his statement, which by another man of science has been 

 expressed in a phrase even more pithy — " Birds are only glorified 

 Reptiles." It is not intended here to enter upon their points of re- 

 semblance and differences. These may be found summarized with more 



^ Cf. Andrews, Rep. Brit. Association {l^svdch. Meeting) 1895, pp. 714, 715 ; and 

 Jhis, 1896, pp. 1-12. 



* Lectures on the Elements o/ Comparative Anatomy p. 69 ; see also Carus, 

 .Ilandbuch der Zoologie, i. p. 192. 



