66 ORGANIZATION OF THE INFUSORIA. 



the centrally enclosed flagellum as a most efficient snare for the capture of 

 food-substances, will be found fully discussed in the systematic description 

 of this special group. Among the Ciliata, an equal or even greater vari- 

 ation in the form and functions of their membraniform appendages may 

 be enumerated. In one remarkable type, Torquatella, referred, however, 

 with some diffidence to the Ciliata, a terminal frill or collar-like expansile 

 and contractile membrane represents the only organ of locomotion and 

 prehension. In Pleuronema, Uronema, and Baonidium, a delicate hood- 

 shaped membrane is let down in front of the mouth when the animalcule 

 is feeding, forming thus a bag-like trap, into which food-particles are 

 swept by the adoral ciliary currents. In Lembus and Proboscella the same 

 purpose is accomplished by the assistance of a more or less prolonged 

 crest-like membrane, which is produced from the anterior extremity 

 alongside of the adoral groove to the ventrally located oral aperture. As 

 a supplementary element to the ordinary adoral fringe of cilia, a band-like 

 undulating membrane is of constant occurrence in association with the 

 Heterotrichous and Hypotrichous genera, Condylostoma, Blepharisma, Ony- 

 chodromus, and Stylonychia, while in Euplotes patella, and in various species 

 of the genus Stentor, the adoral fringe itself commences its existence as a 

 similar simple band-like membrane. In the Holotrichous family of the 

 Ophryoglenidae, again, embracing some dozen genera, all of the members 

 are characterized by the possession of a small flap or clapper-like mem- 

 brane, which is enclosed within, or projects to a less or greater distance 

 beyond the oral fossa. 



It is obvious that the locomotive and prehensile appendages of the 

 Tentaculifera, including Acineta and its allies, depart widely in form and 

 function from those pertaining to the more ordinary Ciliate and Flagellate 

 groups, approaching more nearly in this respect the pseudopodia of the 

 Radiolaria. This affinity is more especially apparent in such types as 

 Ephelota trold and Hemiophrya gemmipara, in the former of which none, 

 and in the latter a portion only, of the tentacle-like organs exhibit the more 

 frequent tubular and suctorial character, being simply prehensile, and in 

 some instances invertile. In the genus OpJiryodendron the single or several 

 extensile proboscidiform tentacula, with their associated terminal fibrillae, 

 exhibit a complex type of structure whose true significance yet requires 

 elucidation. Notwithstanding, however, the humble Radiolarian affinities 

 apparently indicated by the most simply organized members of this group, 

 it has yet to be borne in mind that the embryonic forms of all the species, 

 as yet investigated, are more or less completely clothed with fine vibra- 

 tile cilia, a circumstance which would seem to betoken an adult type of 

 organization in advance even of that possessed by the permanently ciliate 

 group usually accepted as representing the highest section of the Protozoic 

 sub-kingdom. The more important bearings of the organization of the 

 Tentaculifera in this connection will be again referred to. 



