146 NATURAL HISTORY. 



assemblage of animals, bound together by no recognisable 

 bond, and comprising groups having no real affinity with 

 each other. 



The Invertebrate animals had early been a favourite 

 study with Cuvier, and he soon recognised the unnatural 

 collocation of the groups composing the Linnean Vermes. 

 As early as 1795, therefore, he came to the conclusion that 

 the Invertebrate animals could be divided into six ' classes' 

 namely, the Mollusca, the Crustacea, the Worms, the 

 Insects, the Echinoderms, and the Zoophytes. Further 

 researches convinced him of two other points namely, that 

 certain of these groups were of a rank higher than that 

 assigned to ' classes,' and secondly, that certain of them 

 were so closely related together as to be properly refer- 

 able to a single division. Ultimately, therefore, Cuvier 

 divided the entire series of the Invertebrate animals into 

 three great ' embranchements,' or, as we should now say, 

 'sub-kingdoms,' to which he gave the names of the 

 Mollusca, the Articulata, and the Radiata. In the sub- 

 kingdom of the Mollusca he placed the animals which we 

 now know as l Molluscs,' the barnacles and acorn-shells 

 (Cirripedes) being, however, erroneously included among 

 the true shellfish. The Articulata of Cuvier comprised 

 the Ringed Worms (Annelides), the Crustacea (lobster, 

 crab, &c.), the spiders and scorpions (Arachnida), and 

 the true insects (Insecta). Lastly, in the division of the 

 Radiata, or ' Radiated Animals,' Cuvier included five large 

 groups namely (i) The Echinoderms (sea-urchins and 

 star-fishes); (2) The Intestinal or Parasitic Worms; (3) 

 The Jelly-fishes (Acalephae) ; (4) The Corals and allied 

 animals (Polypi); and (5) The Infusoria, comprising 



