LINNEAN SOCIETY OF LONDON, 2"] 



PRESIDENTIAL ADDRESS, 1922. 



OUSEUA'ATIONS ON CeOSSOPTEHYGIAN AND AuTllRODlRAX FiSlIES. 



Among rhe scientific conteinporaries of Liniiseus there were some 

 who failed to realise the influence which his ' Systenui Naturae ' 

 was destined to have on the future progress oF hiology. t)f these 

 perhaps the most famous was tlie Dutch anatomist, Peler Camper, 

 the bicentenary of whose hirth falls within tlie present month. 

 He not only published criticisms of part of Liiiiiseus' systematic 

 work, but also had so little appreciation of the important advance 

 made by his new scheme of classification and nomenclature that 

 he would scarcely admit it to be science. When he was invited 

 to become a Eoreigu Member of this Society in 1788, he even 

 refused to do so on the ground that he could not be associated 

 with any institution which was named after Liniueus. Campers 

 original letter, which is still in the archives of tlie Society, is 

 written in terms so emphatic that there can be no mistake as to 

 his meaning. The lack of mutual appieciation between compara- 

 tive anatomists and systematists, which has sometimes been 

 manifest in later years, evident^' dates back to the beginning of 

 the new era inaugurated by Linnaeus himself, and e\en at that 

 time tended to prevent co-operation. 



There is no subject in which the combined resources of the 

 comparative anatomist (now morphologist) and the systematist 

 are more needed tlian the interpretation of the links which lived 

 in the Devonian period between the fishes and the early 

 amphibians, which were then appearing. They are very different 

 from the forms which might iuive been anticipated, had we been 

 able to deduce them solely from a knowledge of the existing fauna. 

 They therefore afford an interesting illustration of the importance 

 of the study of fossils as an aid to understanding the life of the 

 present day. 



It has long been recognised that, among existing animals, the 

 Dipnoan fishes, Lepidosiren, Frotoptcnis, and Ceratodus, are most 

 nearly intermediate between fishes and amphibians ; but we now 

 learn from fossils that the Dipnoi have remained essentially 

 unchanged since their earliest known occurrence in the Middle 

 Devonian *. They have in the interval merely abandoned the 

 fusiform shape which is adapted for free-swimming lif'% and have 

 become mores or less eel-shaped in ada])tation to a wriggling and 

 grovelling existence at the bottou) of the rivers to which the last 

 survivors retreated by the end of the Mesozoic era. They are 

 therefore excluded by the nature of their dentition, their head- 

 bones and other characters, from con.iideration as the possible 

 ancestors of the Stegocephala (or " Ijabyrinthodonts "), which 

 were the first amphibians. They may have arisen at the same time 

 from a common stock — they probably did so, — but no links have 

 been discovered between them and any true air-breathers. 



* L. Dollo, Bull. Soc. Beige Geol. vol. ix. (189".), pp. 79-128, pis. y.-x. 



