or THE PROTOZOA. CILIATA. 267 



Enchelia by Ehrenberg, which must be separated not only from Stomatoda, 

 but also from the Ciliata. This separation we have carried out, in consti- 

 tuting the two groups Actinophryina and Acinetina, intermediate between 

 Ehizopoda and Ciliata. Excluding these veiy remarkable creatures, the 

 Ehrenbergian families comprehended in our history of Ciliata are the Peri- 

 dinicea, Dinohryina, Vorticellina, Ophrydina, Enchelia, Colepina, Trachelina, 

 Ophryocercina, Aspidiscina, Kolpodea, Oxytrichina, and Euplota. 



Among the Traclielina were enumerated those very simple parasitic beings 

 which late observations have proved to be moutliless, and are referred chiefly 

 to a genus Opalhia. These we therefore abstract, and, treating Opalina as the 

 type, have constituted a new family, Opalincea, a member of the group Astoma. 

 In connexion with this we have placed the very imperfectly known Peridinicea, 

 although some recent writers seem disposed to attribute to them the posses- 

 sion of a mouth and digestive apparatus. The organization of the Dinohryina 

 is, if possible, still less understood ; and since we have no other descriptions of 

 it than those supplied by Ehrenberg, we shall allow it to be mustered with 

 the other ciliated families named in the large group of Stomatoda. 



GeOIJP a. AsTOMA, ASTOMATOUS OH MoUTHLESS CiLIATA. 



FAMILY I.— OPALIN^A. 

 (Plate XXII. 46, 47.) 



Geneeal Characters and Functiois^s. — This family, represented by the 

 genus Opalina, consists of minute miscroscopical animalcules, moved by vibra- 

 tile ciha distributed generally over the body, without mouth, of an oval or 

 oblong compressed figure, living parasitic in the interior of larger animals, 

 upon whose juices they nourish themselves. Their contents consist of a 

 finely-granular substance, hoUowed out into a small number of vesicular 

 spaces, mth no contractile poAver ; extending through the centre is an elon- 

 gated band-like (Hgulate) nucleus, enclosed by a definite but delicate mem- 

 brane, and composed of a homogeneous finely- granular substance. In two 

 species, 0. Planariarum and 0. uncinata (XXII. 46, 47), a large pulsating 

 vascular canal is found ; the latter species is also fm-nished mth strong hooks, 

 whereby it efi'ects its attachment to the intestinal surface, from which it draws 

 its nutriment. Propagation takes place by transverse self- division, and also, in 

 the opinion of a few observers, by germs or embryos. The OpaUna3 are com- 

 posed of sarcode enveloped by an integument, and rapidly imdergo difliuence. 

 In several species the existence of a mouth has been surmised, — for instance, 

 by Ehrenberg in Bursaria {Opalina) JRanarum, and by Dujardin in Opalina 

 Lumhrici. All doubt on this point may be always removed, Stein tells us 

 {op. cit. p. 181), by using chemical reagents, such as alcohol, acetic acid, or 

 weak solution of iodine, which destroy the fold, and prove no real opening to 

 exist. If further proof were wanted, the constant absence of foreign particles 

 in the interior might be adduced. This absence of a mouth afi'ords evidence 

 of the merely transitional nature of Opalincea ; for the same featiu'e prevails 

 in the case of embryos produced from the Acinetina, &c. 



The vesicles or, as Dujardin calls them, " vacuoles," seen in greater or less 

 number in all the Opalincea, are irregularly disposed in the interior, and, 

 according to this author and Stein, have no limiting membrane. However 

 this may be, they remain clear and transparent when the rest of the contents 

 are coloured by the bile of the animals the Opcdina3 inhabit. This fact, 

 moreover, attests another, Aiz. that they cannot owe theii' formation to fluids 

 received from without, but that it must depend on the pecuhar properties of 

 the contents themselves. The formation of vacuoles in Opcdina? was adduced 



