THE EVIDENCE FROM MISSING LINKS. 165 



tilian, and unlike those of the bird ; and these flying dragons possessed 

 prominent jaws, usually furnished with socket-implanted teeth. The 

 Pterodactyls are thus not markedly bird-like in any sense. They do 

 not lie in the direct line, nor form one in the series of links between 

 birds and reptiles, but apparently represent a bird-like but inde- 

 pendent offshoot of the reptilian branch. In any view of their nature, 

 however, they serve to show plainly and forcibly the modification of 

 the reptilian type for flight It requires but a limited draft upon 

 speculative philosophy to support the belief that reptile modification 

 in another direction, and certainly at an epoch anterior to the appear- 

 ance of the Pterodactyls, probably produced the modified birds of 

 which our existing ornithology is the collective product. 



Space fails us in the endeavour to describe other examples of 

 animals which from their anomalous structure seem to connect very 

 diverse types of living forms. Mention might be made of the 

 interesting fact that the apparently distinct groups of living and 

 extinct crocodiles are linked together in a very exact fashion by 

 their bodily structure ; or, conversely, that it is easy to conceive of 

 the varied crocodiles known to science, as having originated by 

 modification of a common type. The mere mention of such fishes 

 as Lepidosiren and Ceratedus, linking their class to that of the frogs 

 or amphibians ; or of such a mammal as the Ornithorhynchus (the 

 " Duck-billed Water-mole " of Australia), with its bird-like skeleton, 

 and other structures of avian nature, suggests to the naturalist the 

 idea that such anomalies are after all only to be accounted for by a 

 theory of nature which postulates the necessity for "links " binding 

 together groups which, at first sight, appear" of widely varied and 

 distinct nature. 



Summing up the results of this investigation in search of " missing 

 links," what may be regarded as the results of our labours ? and to 

 which side does the weight of evidence lead? to evolution and 

 modification as the parent of all that' is in living nature, or to rigidity 

 and fixity of type and form, as the rule and way of life at large ? 

 Judged by a very ordinary standard of value, the evidence appears 

 overwhelmingly strong in favour of the former view. The demand 

 for " missing links," as necessary features of the evolutionist's 

 scheme of creation, is not left unanswered where just cause is 

 shown for the production of these connections between the life of 

 the past and that of the. present. There is neither wildness nor 

 absurdity in the idea that the bird-stock began in animals resembling 

 Compsognathus and its neighbours, and that through modified bird- 

 forms probably resembling the living ostriches and their allies 

 the further and higher development of our existing bird life was 

 gradually evolved. The exact stages of such development we are 

 unable to picture. The sketch is as yet in meagre outline; but the 



