4^ REVIEWS. 



hnxld of cilia situated in a transverse furrow, but it is devoid 

 of a flagellura, and possesses a mouth and temporary anus. 

 From the position of the mouth Bergh considers that the an- 

 terior pole of a ciliate answers to the posterior pole of a 

 cilio-flagellate or flagellate infusor. 



One theory of more general interest is advanced^ namely, 

 that the Flagellata are the most primitive of Protozoa, and 

 " ferm a starting-point from which the Noctilucse, the Rhi- 

 zopoda, the Cilio-flagellata, and through these the Peritricha, 

 hav€ developed." The main argument for this view is that 

 so many of the Rhizopoda begin life as mastigopods or 

 flagellate forms. One cannot but think, however, that this is 

 making too much of embryological evidence. A priori^ it 

 en^rely seems more likely that a flagellum should have 

 arisen as a differentiated pseudopod than that a pseudopod 

 should have arisen as a degenerated flagellum ; but the evi- 

 dence is altogether too scanty for any very consistent theory 

 to be built upon it. At present it seems to me to be im- 

 possible to say whether the myxopod or the mastigopod 

 should be considered as phylogenetically the older ; and I 

 think, therefore, that the following scheme, devised for my 

 last year's lectures, expresses the relationships of the groups 

 of Protozoa as correctly as the evidence now at our disposal 

 will enable us to do : 



BADIOIAKIA. 

 FOBAMINIFEBA EucllitOllia, &C. CILIATA \^ 



liOiiOSA HELIOZOA 



(Atoella, &c.) Actinomonas 



\ Lieberkubuia \ 



TENTACULIFERA 



CILIO-FLAGELLATA 



\ I ^ 



piioTOPLASTA — Mastigamceba — flagellata -^'^ 

 ^/^(Amoebaj &c.) 



GREGAUINIDA. 



The monera of Haeckel are not included in this scheme, 

 but as these can hardly be considered without further in- 

 vestigation to form a natural assemblage, since they are 

 united upon a single negative character, I think it best to 

 leave them out of consideration for the present. 



