35^ 



THE ORIGIN OF VERTEBRATES 



Two years after I had put forward my theory of the derivation 

 of vertebrates from arthropods, Patten published, in the Quarterly 

 Journal of Microscopical Science, simultaneously with my paper in 

 that journal, a paper entitled "The Origin of Vertebrates from 

 Arachnids." In this paper he made no reference to my former 

 publications, but he made it clear that there was an absolutely 

 fundamental difference between our treatment of the problem ; for 

 he took the old view that of necessity there must be a reversal of 



surfaces in order that the 

 internal organs should be 

 in the same relative positions 

 in the vertebrate and in the 

 invertebrate. He simply, 

 therefore, substituted Arach- 

 nid for Annelid in the old 

 theory. Because of this 

 necessity for the reversal 

 of surfaces he discarded the 

 terms dorsal and ventral as 

 indicative of the surfaces of 

 an animal, and substituted 

 haemal and neural, thereby 

 hopelessly confusing the 

 issue and making it often 

 very difficult to understand 

 his meaning. 



He still holds to his 

 original opinion, and I am 

 still waiting to find out 

 when the reversal of sur- 

 faces took place, for his investigations lead him, as must naturally 

 be the case, to compare the dorsal (or, as he would call it, the 

 hsemal) surface of Bothriolepis, of the Cephalaspida-, and of the 

 Pteraspidse with the dorsal surface of the Palseostraca. 



All these ancient fishes are, according to him, still in the arthro- 

 pod stage, have not yet turned over, though in a peculiarly unscien- 

 tific manner he argues elaborately that they must have swum on 

 their back rather than on their front, and so indicated the coming 

 reversal. Because they were arthropods they cannot have had a 



Fig. 143. — Under-Surface of Head-Eegion 



in Tbemataspis. (After Patten.) 



