2G6 THE GEXESIS OF SPECIES. [Chap. 



importance, all point to such a mode of specific mani- 

 festation. 



One very good illustmtion has l>een adduced hy Pro- 

 fessor Flower in the introductory lecture of his first 

 Hunterian Course.^ It is the reduction in size, to a gTeater 

 or less doLrree, of the second and third digits of the foot 

 in Australian mai^supials, and this, notwithstanding the 

 very different form and function of tlie foot in difl'erent 

 groups of those animals. 



A similarly significant evidence of relationsliip is afforded 

 by processes of the zygomatic region of the skull in certain 

 edentates existing and extinct. 



Again, the relation between existing and recent faunas 

 of the different regions of the workl, and the fact lliat the 

 progress in organization has been for the most part from 

 the more general to the more special, tend to support the 

 doctrine of evolution. 



Almost all the facts brought forward l)y the patient 

 industry of ]Mr. Darwin in support of liis theory of 

 " Xatural Selection " are of course avaihable as evidence 

 in favour of the agency of pre-existing and similar 

 animals in specific evolution. 



Xow tlic new forms must be produced by changes taking 

 place in organisms at, after, or before their birth, either in 

 their embrvonic or towards or in their adult condition. 



Examples of strange Ijirths are sufficiently numerous, 

 and they may arise either from direct embryonic modifica- 

 tions or api^arently from some obscure change in the 

 parental action. To the former category belong the hosts 

 of instances of malformation tlirough arrest of develop- 



^ Introductory Lecture of Febniar^- li, 1870, pp. 24—30, Figs. 1 — 4. 

 (Churchill aud Sous.) 



