OF THE PROTOZOA. CILIATA. 377 



characters, limits, and mutual relations of the families described will form 

 the subject of the Systematic portion of this work. 



The Ciliata, in our meaning, are very nearly the same beings that Ehren- 

 berg called Etiterodela, or Polygastriea furnished with an intestine connecting 

 together their stomach- sacs. A division of the Enterodela was made, accord- 

 ing to the mutual relation in position between the two orifices of the body — 

 the mouth, and anus or discharging vent — into, 1st, Anopisthia, in which the 

 intestine is so curved on itself that its two ends unite together in a common 

 aperture ; 2, Enantiotreta, having an oral opening at one extremity, and the 

 anal at the other, i. e. opposite to each other ; 3, Allotreta, mth the two 

 orifices placed obliquely with reference to one another ; and 4, Catotreta, 

 with both situated on one surface — the abdominal. The subjoined tabular 

 view will display these divisions, and also their subdivision into families. 



We have departed from this arrangement of Ehrenberg chiefly by omitting 

 a few genera and species, viz. Actinoj^hrys, TrichodiscuSj and Podojphrya 

 among the Enchelia, and some species of Bursaria from the TracJielina, and 

 also by adding several new genera and families. Concerning the necessity of 

 detaching the Actinophrys and its two congeners from the Enchelia, no doubt 

 can be entertained when their structure comes to be considered ; we have 

 thrown them together into one family under the name of Actinophryina 

 (p. 243), and have brought them and the peculiar beings known as Acinetina 

 (p. 258) together as two subdivisions of Rhizopoda. The peculiar parasitic 

 BursaricB without mouth constitute, with some similar ciliated mouthless 

 beings, a subdivision of the CHiata, standing in near relation with Gregari- 

 nida, and, in some measure, intermediate between the Ciliata and Rhizopoda. 

 Lastly, we have removed the Ichthydina from the Rotatoria, and treated them 

 as a subclass of Ciliata. The additional families and genera we shall not here 

 specify, but must direct the reader forinformation to the systematic descriptions. 



The following tabular view represents Ehrenberg's classification. 



]■ 



One receiving 



and discharging [ illoricated VorticeUina. 



orifice only for y 



nutrition. [ loricated Ophrydina. 



Anopisthia. 



Two orifices : 



one at 



each extremity. 



Enantiotreta. 



I illoricated EncheHa. 



I loricated Colepina. 



I^mouth furnished with pro- 1 ^ra^helina. 



Orifices situated fiUoricated i boscis, tail absent :-/_, 



obKauelv -i mouth anterior, tail present Ophryocercinfi 



( loricated Aspidisciaa. 



Allotreta. 



Orifices 



abdominal. 



Catotreta. 



f r locomotive organs, cilia Kolpodea. 



illoricated \ 



[ various Ox jtrichina. 



^ loricated Euplota. 



Dujardin's distribution next claims attention. Having, as we have seen, 

 entirely rejected Ehrenberg's polygastric hypothesis, and at the same time 

 failed to recognize many important points of internal organization now 

 well established, he had, to construct his system, recourse to external 



