312 THE DOCTRINE OF DESCENT. 



rerum ex omni specie viventium unicum sexus par fuisse creatum, 

 suadet ratio." 



^' lb. Non multum a veritate me aberratiim confido, si dixerim, 

 omnem continentem terram fuisse in infantia mundi aquis sub- 

 mersam et vasto oceano obtectam, praeter unicam in immenso 

 hoc pelago insulam, in qua commode habitaverint animalia omnia 

 et vegetabilia Isete germinaverint." 



^^ Tot numeramus species, quot ab initio creavit infinitum ens." 



^'^ Geoffroy St. Hilaire wrote to Cuvier : " Venez jouer parmi 

 nous le role de Linne, d'un autre legislateur de I'histoire naturelle." 



^^ Ossements fossiles. 



'^ L. Agassiz, An Essay on Classification, 1859. P. 253: — 



" As representatives of Species, individual animals bear the 

 closest relations to one another ; they exhibit definite relations also 

 to the surrounding element, and their existence is limited within a 

 definite period. 



" As representatives of Genera these same individuals have a 

 definite and specific ultimate structure, identical with that of the 

 representatives of other species," etc. See also P. 261 : — 



" Branches or types are characterized by the plan of their struc- 

 ture; 



" Classes, by the manner in which that plan is executed, as far 

 as ways and means are concerned ; 



" Orders, by the degrees of complication of that structure ; 



" Families, by their form, as far as determined by structure ; 



" Genera, by the details of the execution in special parts ; and, 



" Species, by the relations of individuals to one another, and to 

 the world in which they live, as well as by the proportions of their 

 parts, their ornamentation," etc. 



2° Haeckel, Generelle Morphologic der Organismen (Berlin, 1866). 

 II. 323, &c. 



^' L'espece est — "la reunion des individus descendant I'un de 

 I'autre et des parents communs, et de ceux qui leur ressemblent 

 autant qu'ils se ressemblent entr'eux." Cuvier, Le Regne Animal. 



-^ O. Schmidt, Die Spongien der Kiiste von Algier, 1868, and 

 Versuch einer Spongienfauna des atlantischen Gebietes, 1870. 



^^ Haeckel, Die Kalkschwamme, Eine Monographie in Zwei 

 Banden, Text und einem Atlas mit 60 Tafeln Abbildungen (Berlin, 

 1872). 



