NA TURE 



645 



THURSDAY, OCTOBER 31, 1901. 



P TERODA C T I 'LES. 

 Dragons of the Air: an Account of Extinct Flying 

 Reptiles. By H. G. Seeley. Pp. xiii + 239. Illus- 

 trated. (London ; i\Iethuen and Co., 1901.) Price bs. 

 EVER since the study of fossil remains was taken 

 up in earnest, pterodactyles, or, as the author 

 elects often to call them, ornithosaurs, have attracted 

 the deepest attention on the part of anatomists on 

 account of the many puzzling problems connected' with 

 their organisation and affinities, while from their weird 

 form, peculiar attributes, and the huge dimensions 

 attained by some of their later representatives they have 

 appealed more strongly to popular interest than is the 

 case with many of their extinct contemporaries. Among 

 all the diligent students of the organisation of these 

 strange creatures (so far as it can be worked out from their 

 bones alone) none has been more constant or more per- 

 sistent than Prof. H. G. Seeley, who commenced his 

 investigations when a student at Cambridge during the 

 late 'sixties. At that time the so-called coprolite-works 

 in the Cambridge Greensand were in full swing ; and the 

 rich, albeit much broken, material thus obtained afforded 

 opportunities for studying the structural details of ptero- 

 dactyle bones in a manner impossible when dealing with 

 the embedded skeletons of the smaller forms from the 

 lithographic limestone of the Continent. Of these 

 opportunities — both as regards study and collecting — 

 Prof. .Seeley availed himself to the full ; and from that 

 time to this, as occasion presented itself, he has, we 

 believe, continued faithful to his favourite study. During 

 the latter years of Prof. Sedgwick's tenure of the 

 Woodwardian Chair at Cambridge, Prof. Seeley de- 

 livered a series of lectures at various centres— including 

 the Royal Institution— on pterodactyles ; and the present 

 volume purports to be a reissue of these lectures in an 

 expanded form, with such revision as has been rendered 

 advisable by the progress of investigation. 



In this volume Prof. Seeley appeals, as he tells us in 

 the preface, alike to the general public and to the man of 

 science. To achieve success in this double role is by no 

 means an easy matter ; and it may be questioned whether 

 he has not given too much elementary explanation to 

 suit the latter class of readers and not enough for the 

 needs of the former. This, however, is a matter which 

 concerns an author and his publisher rather than a 

 reviewer. 



All who have been occupied in investigating the oste- 

 ology of pterodactyles can scarcely fail to be struck with 

 the marked similarity presented in many respects — es- 

 pecially in the skull and cervical vertebra — to birds. And 

 this avian resemblance seems to have impressed itself 

 with peculiar force on the mind of the author, who has 

 all along contended that these creatures are not entitled 

 to be ranked as reptiles, but form an outstanding group 

 by themselves, displaying very widespread affinities with 

 other groups of animals. So widespread, indeed, does 

 Prof. .Seeley regard the relationships of pterodactyles 

 that it is by no means an easy matter to understand what 

 his opinions on this subject really are, especially as his 

 NO. 1670, VOL. 64] 



sentences are not unfrequently so involved that it is 

 difficult to grasp his meaning. Even, however, if they 

 cannot agree with them (or in some cases even under- 

 stand them), the views of such an experienced and earnest 

 investigator on a subject he has made specially his own 

 should command respectful attention on the part of those 

 whose knowledge in this respect is less extensive than 

 that of the author. 



Perhaps the best way of endeavouring to convey an 

 idea of the author's views on pterodactyle relationship — 

 which is the leading feature of the book — will be to quote 

 his own words. 



Selecting a few passages in serial order, we find it 

 stated on p. 58 that ' — 



'• While these animals are incontestably nearer to birds 

 than to any other animals in their plan of organisation, 

 thus far no proof has been found that they are birds, or 

 can be included in the same division of vertebrate life 

 with feathered animals." 



On p. 188 we are told that — 



"It is not so much that they mark a transition from 

 reptile to bird, as that they are a group which is parallel 

 to birds, and more manifestly holds an intermediate place 

 than birds do between reptiles and mammals." 



Again, on p. 210 we find the following :— 



"Therefore there is a closer fundamental resemblance 



between some carnivorous dinosaurs \e.g. Coelitrus'] than 



might have been anticipated.'' 



On the following page it is stated that — 



"The dinosaurs, like pterodactyles, must be regarded 

 as intermediate in some respects between reptiles and 

 birds." 



Finally, on p. 223, we have the following : — 



" It would therefore appear from the vital community 

 of structures with birds, that pterodactyles and birds are 

 two parallel groups, which may be regarded as ancient 

 divergent forks ol the same branch of animal life, which 

 became distinguished from each other by acquiring the 

 different condition of the skin, and the structures which 

 were developed in consequence of the bony skeleton 

 ministering in different ways ; and with different habit of 

 terrestrial progression, this extinct group of animals ac- 

 quired some modifications of the skeleton which birds 

 have not shown. There is nothing to suggest that ptero- 

 dactyles are a branch from birds, but their relation to 

 birds is much closer, so far as the skeleton goes, than 

 is their relation with the flightless dinosaurs, with 

 which birds and pterodactyles have many characters in 

 common." 



Other passages might be quoted, but the foregoing are 

 sufficient to indicate the extreme complexity of ptero- 

 dactyle relationship according to the author. Personally 

 we must confess to a total incapacity to draw a mental 

 picture of the relationships thus indicated ; and we have 

 also failed in the attempt to construct a diagram which 

 will show how groups that are divergent are yet parallel. 



We have also yet to learn that birds are in any 

 respect intermediate between reptiles and mammals ; 

 while we totally fail to see how any animals can be, even 

 in sfme respects, intermediate between reptiles and 

 mammals on the one hand, and reptiles and birds on the 

 other. That is to say, in the sense in which we under- 

 stand the term "intermediate," as indicative of descent. 



1 The italics introduced into these quotations are the reviewer's. 



