PETEllS' nANDBOOK OF ZOOLOGY. 41 



due no doubt to a comparative multiplicity of forms with a greater 

 simplicity of organisation. Hence among these lower groups, nearly 

 every writer has his own system, and although none of these efforts 

 may lead to a classification at all comparable for clearness of defini- 

 tion with the well established gTOupings of the higher forms, we may 

 generally find some justification for them. Nevertheless we are 

 rapidly approaching to a uniformity of opinion even as to the classifi- 

 cation of the lowest forms of animal life, such as the Coelenterata 

 and Protozoa, and although each successive author may show us 

 some slight change of the kaleidoscopic picture, its broad and 

 general features remain pretty much the same. 



Dr. Carus indeed in his systematic arrangement of the Protozoa 

 establishes one new class for the reception of JSfoctiluca, to which he 

 gives the name of Myxocystodea, — and in the classification of the 

 other forms he introduces some new groupings. His second and 

 third classes, consisting of the Gregarinse and Spongise, present no 

 peculiarity calling for remark, but in his classes of Ehizopoda and 

 Infusoria we find some new views. Thus the Ehizopoda form three 

 orders, of which the first, under the new name of Homogenea, includes 

 only the Poraminifera, distributed in accordance with a combination 

 of the systems of Carpenter and Max Schultze ; the second, 

 Phloeophora, is established for the Actinophryua, and the third, 

 Cytophora (Hackel), contains the w^hole of the Eadiolaria of J. 

 Miiller. The latter are arranged in accordance with Hiickel's distri- 

 bution, and Dr. Carus has gone so far as to give a complete analysis 

 of the multitudinous genera proposed by that author. "Whatever 

 may be the value hereafter attached to Hackel's work, this analysis 

 cannot but prove welcome to the working naturalist. 



The presence of a nucleus and contractile vesicle in Amceha and 

 its allies induces Dr. Carus to remove these singular creatures from 

 the class of Ehizopoda, of which they have generally been regarded 

 as typical examples ; they constitute the first order, Atricha, of his 

 Infusoria. His second order, Suctoria (Clap, and Lachm.) includes 

 only the Acinetina, the right of which to a distinct place in the 

 system is, however, still disputed by Stein. The true Infusoria consti- 

 tute a third order, to wdiich Ehrenberg'snameCiliata is appropriated, 

 and a fourth gToup the Elagellata (Ehrenb.), includes several families 

 such as the Peridima, Yolvocicea, and Monadina, the animal nature 

 of which is, to say the least of it, very doubtful. The last mentioned 

 order is, however, inserted only provisionally. 



We have thus, not without some labour, endeavoured to analyse 



