56 



INVERTEBRATE ANIMALS. 



thirdly, an assemblage of zooids produced by budding or fission from 

 a primitive being, but not necessarily remaining connected with, one 



Fig. 2'.!.— A, Part nf the colony of Bougainf'dka muscus, one of the coniiiound 

 llijilrozDii, of tlie natural size. B, Part of tlie same enlargtd : J9 A polypite fully 

 expanded ; m An incompletely developed reproductive bud ; tn' A more completely 

 developed reproductive bud ; /"Cccnosarc with its investing periderm and central 

 canal. C, A free reproductive bud or medusiform gonophore of the same : it Gono- 

 calyx; %> Manubrium; c One of the radiating gastro-vascular canals; o Ocellus; 

 V Velum ; t Tentacle. (After AUmau.) 



another or exhibiting any common features of likeness, as we shall 

 see is the case in many of the Hydrozoa. Lastly, cases may occur 

 in which the individual consists partly of similar zooids which 



