352 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 
hemal and neural, thereby 
hopelessly confusing the 
issue and making it often 
very difficult to understand 
his meaning. 
He still holds to. his 
Fig. 143.—Unprr-Surrace or Hrap-RzGIon original eee, and IT am 
in TRemartaspis, (After Parren.) 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 
hemal) surface of Bothriolepis, of the Cephalaspide, and of the 
Pteraspide with the dorsal surface of the Palzostraca. 
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 
