FOSSIL PEDIGREES 83 



the palseontological argument is lost. It would be prepos- 

 terous for the progeny to be prior to, or even coeval with, the 

 progenitor, and so we must be quite sure that what we call 

 "posterity" is really posterior in time. Now the sole argu- 

 ment that palaeontology can adduce for the posteriority of 

 one organic type as compared with another is the negative 

 evidence of its non-occurrence, or rather of its non-discovery, 

 in an earlier geological formation. The lower strata do not, so 

 far as is known, contain the type in question, and so it is con- 

 cluded that this particular form had no earlier history. Such 

 an inference, as is clear, is not only liable to be upset by later 

 discoveries, but has the additional disadvantage of implicitly 

 assuming the substantial completeness of the fossil record, 

 whereas the absence of intermediate species is only explicable 

 by means of the assumed incompleteness of the selfsame record. 

 The evolutionist is thus placed in the dilenm:ia of choosing 

 between a substantially complete, and a substantially incom- 

 plete, record. Which of the alternatives, he elects, matters 

 very little; but he must abide by the consequences of his de- 

 cision, he cannot eat his cake and have it. 



When the evolutionist appeals to the facts of palaeontology, 

 it goes without saying that he does so in the hope of showing 

 that the differences, which divide modern species of plants and 

 animals, diminish as we go backward in time, until the stage 

 of identity is reached in the unity of a common ancestral 

 type. Hence from the very nature of the argument, which 

 he is engaged in constructing, he is compelled to resort to 

 intermediate types as evidence of ^the continuity of allied spe- 

 cies with the hypothetical ancestor, or common type, whence 

 they are said to have diverged. Now, even supposing that 

 his efforts in this direction were attended with a complete 

 measure of success, evidence of this kind would not of itself, as 

 we shall see, suffice to demonstrate the common origin of the 

 extremes, between which a perfect series of intergradent types 

 can be shown to mediate. Unquestionably, however, unless 

 such a series of intergradent fossil species can be adduced as 



