PHYLOGENY OF VERTEBRATES, 193 
the individual history of human development, we have 
already recognized the undeniable fact that, in developing out 
of the egg, man at first does not differ from other Vertebrate 
animals, and especially from Mammals, we must necessarily 
come to the conclusion, in regard to the paleontological 
history of his development, that man _ has, historically, 
actually developed out of the lower Vertebrata, and that he 
is directly derived from lower Mammals. This circumstance, 
together with the many high interests which, in other 
respects, entitle the Vertebrata to more consideration than 
other organisms, justifies us in examining the pedigree of 
the Vertebrata and its expression in the natural system, 
with special care. 
Fortunately, the records of creation, which must in all 
cases be our guide in establishing pedigrees, are especially 
complete in this important animal tribe, from which our 
own race has arisen. Even at the beginning of our century 
Cuvier’s comparative anatomy and paleontology, and Bar’s 
ontogeny of the Vertebrate animals, had braqught us to a 
high level of accurate knowledge on this matter. Since 
then it is especially due to Johannes Miiller’s and Rathke’s 
investigations in comparative anatomy, and most recently 
to those of Gegenbaur and Huxley, that our knowledge 
of the natural relationships among the different groups of 
Vertebrata has become enlarged. It is especially Gegen- 
baur’s classical works, penetrated as they are throughout 
with the fundamental principles of the Theory of Descent, 
which have demonstrated that the material of comparative 
anatomy receives its true importance and value only by the 
application of the Theory of Descent, and this in the case 
of all animals, but especially in that in the Vertebrate tribe. 
