LINNEAN SOCIETY OF LONDON. XXI 



mained there four years with Mr. "Wallace, and seven years more 

 after his companion had left him. Since his return to England, he- 

 sides the rich harvests he had made as a zoological collector, he has 

 fully proved how eminently he was also qualified to make those ob- 

 servations we expect from a travelling naturalist. His valuable 

 paper on the Hehconidae of the Amazon Valley, in the last part of the 

 twenty-third volume of our Transactions, aims especially at a prac- 

 tical illustration of changes taking place in strict conformity with the 

 Darwinian hypothesis ; and the observations connected with zoolo- 

 gical and especially entomological biology dispersed through his 

 ' Naturalist on the Amazons ' bear frequently on those concurrences 

 of circumstances which may influence the preservation of what we 

 usually term accidental varieties, and the gradual extinction of 

 typical forms. 



Dr. Carpenter's great work on Foraminifera is pregnant with facts 

 illustrative of an unbroken continuity of animal descent from the 

 earliest geological periods where remains can be traced to the present 

 day. Dr. Falconer's elaborate paper on Elephants, recent and fossil, 

 in the third volume of the Natural History Review, exhibits, as far 

 as can be ascertained from teeth alone, on the one hand, long periods 

 of fixity of type in some of the species, and on the other hand close 

 aflS.nity between the extinct Elephants of Europe and some of the 

 Indian ones which preceded or followed them. Professor 0. Heer and 

 Count G. de Saporta's independent researches on the European Flora 

 of the Tertiary period, notwithstanding the more than doubtful de- 

 termination of the majority of the fragments described, yet, in the few 

 that can be satisfactorily ascertained, show a much closer connexion 

 with recent vegetation than had been hitherto supposed. All descrip- 

 tive works, in short, now published in which species are considered in 

 a general point of view, with reference to their areas, geographical re- 

 presentatives, and affinities, recent or extinct, must furnish data of 

 more or less importance to the investigator of historical biology. 



As a general result it appears to me that the tide of opinion among 

 philosophical naturalists is setting fast in favour of Mr. Darwin's 

 hypothesis. The accuracy of his facts is no longer contested, and 

 much of his reasoning must be admitted as unanswered and unanswer- 

 able. There are, I believe, few, if any, who really consider the sub- 

 ject, who would now deny that great, though very gradual, changes 

 do result from those successive concurrences of phenomena figura- 

 tively called natural selection, or that there is every probability that 

 a considerable number of what we term alHed species may be de- 

 scended from some common ancestor, which, if presented to us, We 



