HYrOTRICHOUS INFUSORIA. 



371 



31. CHLAMYDODON 

 MNEMOSYNE. 



A, Under, B, side view. 



Ophrydi/u/nt Eichhornii (Fig. 30) is an example, and it forms attached gelatinous masses in which 

 are numerous individuals, each with its slender pedicle. The body is long and narrow, and the 

 whole is very elastic. They live in fresh water, attached to Anacharis, and about a hundred may 

 be in a mass measuring ^th of an inch. They increase by transverse as well as by longitudinal 



fission. 



SUB-ORDER HYrOTRlCHA. 



These animalcules are free swimming, and the locomotive cilia are confined to the inferior or 

 ventral surface, and are often modified into setae and hooks. The superior surface 

 is either smooth, or has some immobile setae on it. The mouth and anus are ventral. 

 Saville Kent subdivides this group into six families and forty-two genera. 

 Chlamydodon mnemosyne is the type of one family, and it has a short, kidney- 

 shaped body, the front being wide and the dorsal surface convex, and the 

 ventral having a striated border. The cilia are the most conspicuous anteriorly, 

 and they project as a fringe. The oral aperture has a bundle of rods in its mem- 

 brane. The endoplast is single and ovate, and there are many contractile vesicles. 

 It inhabits salt water (Fig. 31). 



Another family, the Dysteriidae, mostly inhabit salt water, and these free 

 swimmers are mostly provided with a lorica either single or made up of two joined or detached 

 valves like a small crustacean. The cilia are on the lower surface and the 

 oral aperture leads to a canal, or pharynx, with a horny tube, or rods. The 

 ' animalcules have a conspicuous tail-like style, or a group of setae. 



Dysteria armata, a salt-water form, Tr^th to -g^th of an inch in length, 

 is remarkable for the anatomy of the pharynx. The oral fossa has a curved 

 rod which terminates in fork-like teeth, and which is lost in the walls of 

 the fossa. Then comes the armature of the pharynx, which consists of two 

 portions an anterior rounded mass in opposition with a much elongated 

 styliform posterior portion. These animalcules live in swarms among the 

 confervoid Algae which coat the shells of limpets and periwinkles (Fig. 32). 



The family Peritromidae has the ventral surface finely ciliate, and tluire 

 Fig. 32. DYSTEIUA is a curve of powerful cirri around or near 

 AKMATA. (After Huxley.) the mouth, and the pharynx is unarmed. 

 A, Left side ; B. a, pharyngeal A1 ,, ., , . . , . , 



apparatus. A host or flexible or persistent m shape 



animalcules, with front, ventral, and rear 



styles, and hooks and setae at the margin, belong to the Oxytri- 

 chidae. The common Stylonychia mytilus is an admirable ex- 

 ample. It has a hard covering, or lorica, and the neighbourhood 

 of the mouth has a great curve of long cilia on an undulating 

 membrane. There are usually eight styles in front, five claw-like 

 hooks on the ventral surface, and five straight anal styles. The 

 marginal setae form a border, and there are three long tail-like setae. 

 There are two endoplasts, sometimes divided, and a contractile 

 vesicle. It inhabits fresh water, and the largest are T Vnd of an inch 

 long (Fig. 8). 



Another species (Stichotricha remex, Fig. 33) has the cilia of 

 the apex of the peristomial border very long, and the body is A, Animals in tubes ; B, free animalcule ; c.dia- 



J * gram of Schizosiphon. 



lanceolate, and inhabits a slender, brown tube, 



three or four times as long as the body, which projects from it with a twist. 



Closely allied to these dwellers in separate tubes is a species (Schizosiphon 

 socialis) which forms colonies that build up a branching tube. Another of this 

 great family is Uroleptus piscis, and it is remarkable for its attenuated end, two 

 endoplasts, and great curved ciliated peristome. 



A family of the Hypotricha has no setae along the margin, or they are rudi- 

 mentary, but there is a lorica, and there are ventral and anal styles, or else hooks. In Euplotes 



Fig. 34. -ETJPLOTES 



CHARON. 



