CARPENTER ON THE ABEAM; MM EXT OF THE RHIZOPODA. 169 



perforated. Any arrangement more truly unnatural can scarcely be 

 conceived : — to flW it appears a ^Ori of mhn-tio ad obtainl 'inn of the 

 principle that the unilorwlarity or inullilocularily <>1' 1 lie* AvA\ slmuld 

 be held of primary account in the >yslematic arrangement, hi 

 organisms in (jiu-stion. 



An important step in the chissi jicnt ion of the Riiizopoda was 

 made by the late Prof. Johann Midler, in his admirable memoir 

 (Transactions of the Berlin Academy, Lsos), 4l LYticr die Thalaasi- 

 collen, Polycysfinen, und Acanthovictrtn des Alii telmecres ;"' these 

 three groups, whose mutual allinity lie showed to lie very strong, 

 being associated by him into a distinct sub-class, which lie distin- 

 guished as Rhizopoda Radiolabia. lie failed, however, to perceive 

 what appears to me to be the essential relationship between the 

 Acantliometrina and Actinophryna ; an Acanthometra, as we shall 

 presently see, being nothing else than an Actinophrys furnished w ith 

 a siliceous skeleton. And in drawing a strong line of demarcation 

 between the simple and the composite forms of Thalassicolina, he 

 endeavoured to establish a distinction which seems to me untenable 

 among animals that multiply by gemmation, between the simple and 

 the composite forms. Taking the group of Radiolaria as a whole, 

 however, it may be considered an eminently natural one ; and I adopt 

 it as one of the primitive sub- divisions of the class, adding to it the 

 family Actinophryna, which includes Actinophrys and its immediate 

 allies, for reasons which will be presently apparent. 



More recently an attempt has been made to frame a natural 

 classification of the Rhizopoda as a w T hole, by two distinguished 

 pupils of Prof. Muller, MM. Claparede and Lachmann (" Etudes sur 

 les Infusoires et les Rhizopodes" Geneve, partie 2ieme, 1859) ; and 

 it is with some diffidence that I venture to express a divergence of 

 opinion from observers who have been trained in so excellent a school, 

 and who have given such ample proofs in their published writings of 

 practical familiarity with the several forms whose relations they dis- 

 cuss. The following is the scheme proposed by them (1. c. p. 4-31): — 



Orders. Families, 



f No silicious spicula } p ROTEIVA f *• Amoebina. 



No calcareous 



test 

 No multiple- 

 porous cham-^ 

 bers 



Pseudopodia 

 rarely <( 



No yellow cells S 



uniting 



Silicious spicula 

 Yellow cells 



Pseudopodia 

 form in;. 



;iinii<T< 

 ^ junctions 



Dpodia *} 

 -very f 

 orous / 

 tions J 



A usually calcareous test, ^ 

 most frequently multilocular: 



' even wben there is but a sin- ! 

 gle chamber, its parietes are ( 

 traversed by a multitude of j 



L pores J 



\ ECHINO- 



] CVST1DA 



Gkomid.v. 



FOKAMI- 



MFJEKA 



£ 2. Actinophryna. 



C I. Acantliometrina. 

 •J 2. Thalassicollina. 

 ( 3. Polycystina. 



Gromida. 



{ 1. VlolMitl, 



( -J. l'olythalamia. 



