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Mendelo-mutationist theory than by Darwinism. When the 

 origin of a species, perhaps known from many hundreds of 

 individual fossils, cannot be traced, the classic Darwinian ex- 

 planation is that it was evolved somewhere else, or that the 

 particular stratigraphical zone, or fraction of a zone, in which it 

 was evolved has been washed away. And, of course, it is true 

 that negative evidence is most inconclusive in geology; but 

 negative evidence in this instance is cumulative, and since it is 

 not a few species of animals that must have been evolved 

 " somewhere else," but thousands of species, one begins to 

 suspect that the theory requires serious modification. No 

 palaeontologist would be so rash as to dogmatise on such a 

 difficult subject, but the study of fossil species from this point 

 of view might well be pursued further than it has been 

 hitherto. 



And now if we confine our attention to the narrow depart- 

 ment of human palaeontology, we find the same phenomena ; 

 namely, constancy of species in time, and gaps between species. 

 The facts relating to fossil men are regrettably few, but they are 

 interesting, and the discoveries fall at once into two groups. 

 Homo sapiens, real man, is known fossil ; that is one class of 

 evidence. The other class of evidence is the occurrence of 

 fossils of creatures who, although members of the human tribe, 

 are not placed in the species Homo sapiens. This multiple 

 character of the evidence is masked by the continued use of the 

 word Paleolithic, and still more by the mischievous expression 

 " Paleolithic man." The term Paleolithic was appropriate enough 

 forty years ago, when we knew only of a vague " Older Stone 

 Age" more ancient than the Neolithic Period, but it merely 

 serves now to cover up the fact that the pre-Neolithic Hominidae 

 are known to be extremely heterogeneous. Hence I proposed 

 in Science Progress for October, 191 3, that the Late Paleolithic 

 Period, that in which Homo sapiens is found, should be renamed 

 the Deutolithic Period, and that the Early Paleolithic Period, 

 the strata of which contain remains of the extinct species of the 

 Hominidae, should be styled the Protolithic. These names 

 Protolithic and Deutolithic are formed on analogy with the terms 

 Protozoic and Deutozoic, which signify of course the two great 

 divisions of the Paleozoic era. 



The Deutolithic strata contain, therefore, relics of our own 

 species only, but the remains of several different races have been 



