ON TILE GROUP PROTOZOA. 37 



These organisms are true animals. Eecent observations,* it may be 

 said, throw some doubt over the nature of a few of the simple Rhizopods, 

 but they are far from proving their supposed affinities with plants. 

 And, until further researches compel us to alter our belief, we see no 

 sufficient reason for dissenting from the generally-received opinion, that 

 Ama3ba and Actinophrys perform all the necessary functions of un- 

 doubted animals. With regard to Infusoria, if the possession of a 

 mouth be demanded as an essential condition in all future definitions of 

 this group, we at once get rid of the hosts of Rhizopods and vegetable 

 forms, which some, following Ehrenberg, still associate with the Infu- 

 soria properly so called. It yet remains to distinguish these latter from 

 the numerous embryonic forms of higher animals, more particularly 

 of Annulloida, with which, in all probability, they are in many cases 

 confounded. 



A good classification of the Protozoa is still a desideratum. Much 

 has yet to be done towards the attainment of a more perfect knowledge 

 both of their structure and development, before even the data necessary 

 for such an object can rightly be perceived. How far, in the present 

 state of inquiry, we seem justified in indicating the outlines of a natural 

 arrangement, may be inferred from the following considerations. 



Some of the Protozoa possess, others are destitute of, a mouth. The 

 former are termed Stomatoda, the latter, Astomata.f The Stomatoda 

 include all the Infusoria proper, and the solitary genus Noctiluca. Under 

 Astomata are placed all remaining Protozoa. Whether the six groups 

 of Protozoa Astomata, recognized in the above list, be precisely equiva- 

 lent to one another, must remain an open question. By J\ Miiller J the 

 term Rhizopoda has been extended, so as to include the Polycystina, 

 Thallassicollidge and Acanthometra. To these three groups he applies 

 the collective designation of Rhizopoda radiolaria. Lachmann, and 

 Claparede,§ the latest systematic writers on this subject, have, with some 

 few restrictions, adopted the views of Miiller, and arranged the Rhizo- 

 poda as follows : — 



RHIZOPODA. 



No calcareous 

 shell, with 

 numerous, 

 porous, 

 chambers. 



f Xo siliceous spi-"| 

 cules, or yel- <• PR( 

 low cells. J 



Orders. Families. 



f] 



Pseudopodia g-VJf *~ f PHOTEIXA. \ ^^RTBi.. 



rarely becom- ! 10w ceus - ■> L 



one ShS th I Siliceous spicules! (1. Acanthometrina. 



oneanotner. and yellow J-ECHINOCYSTIDA. 1 2. Thalassicollina. 



L Cells. j (,3. POLTCISTINA. 



, Pseudopodia forming very nume-) rpoviD , . r „ , frTl , 



I rous, confused, agglutinations. JWKMUUA- 1. (*romida. 



A shell, usually calcareous, most frequently divided! " f, ».„,„„„,„„ 



into several chambers, each of which, though entire, \ FORAMINIFERA. { , p r ? r v ' "f r f" A A> 

 has its walls pierced with very many pores. I r louI hal amia. 



* Hartig, in "Quart. Jour. Micr. Sci.," 1855, p. 51; Carter, in "Ann. Nat. Hist.," 

 1857, p. 259 ; A. de Bary, in Siebold und Kolliker's "Zeitschrift," 1859, p. 88; Dick- 

 son, in "Quart. Jour Micr. Sci.," 1860, p. 7. 



f Huxley, " Lectures on Gen. Nat. Hist.," in " Med. Times and Gaz.," May 24, 1856, 

 p 507. % Miiller's Archiv., 1858, p. 104. 



§ Etudes sur les Infusoires et Ithizopode.s, 2me livraison, p. 434. 



