GENUS PHASCOLODON. 745 



which is usually curved towards the right ; the oral aperture nearly median ; 



cuticular surface striate longitudinally ; pre-oral cilia most conspicuous ; 



trichocysts distributed unevenly throughout the anterior or neck-like region ; 



contractile vesicles five in number, dispersed in a line along the left border 



of the body; endoplasts spheroidal, subcentral. Length 1-250". 



Hab, — Fresh water. 



The large number of contractile vesicles serves to distinguish this species 

 from Z. fasciola, which in other respects it closely resembles. 



Litonotus diaphanus, Wrz. 



Body elongate-lanceolate, elastic and flexible, flattened, about six times 

 as long as broad, tapering at each extremity, the anterior one most attenuate 

 and neck-like, directed slightly towards the left ; parenchyma granular 

 throughout, food-substances permeating the neck-like region as well as the 

 general body portion ; the cuticular surface longitudinally striate on the 

 ventral aspect ; trichocysts very long and slender, distributed irregularly 

 throughout the cortical layer ; contractile vesicles six in number, disposed 

 in a line along the right-hand border ; endoplasts two in number, ovate, 

 united by a cord-like filament. Dimensions unrecorded. 



Hab. — Fresh water. 



This type is distinguished by the character of the parenchyma, which is granular 

 throughout, and permits the passage of food-particles into the more attenuate neck- 

 like portion, whereas in the preceding species it is retained within the central or 

 body portion only. The trichocysts are also longer and more slender, and irregularly 

 distributed throughout the substance of the cortex. Wrzesniowski has regarded 

 these two characters of the parenchyma and trichocysts as of sufficient importance 

 for the institution on this animalcule of a separate subgenus, which he proposes to 

 distinguish by the title of Hemiophrys. 



Fam. II. CHLAMYDODONTIDiE, S. K. 



Animalcules free-swimming, ovate, with a convex dorsal and flattened 

 ventral surface ; the cuticle elastic or indurated ; the ventral surface more 

 or less completely clothed with fine vibratile cilia ; the oral aperture opening 

 on the ventral surface, followed by a tubular pharynx, the walls of which 

 are strengthened by a cylindrical fascicle of corneous rods or a simple 

 corneous tube; no stylate appendage or fascicle of caudal setae at the 

 posterior extremity. 



The members of this family group, which corresponds with the Chlamydodonta 

 of Stein, as characterized in the second but not the first volume of his ' Organismus,' 

 are to be distinguished from those of the following family or Dysteriidse by the 

 entire absence of the caudal style or fascicle of setse at the posterior extremity. 

 Otherwise, and more especially with regard to the character of pharyngeal armature, 

 the two groups are closely related. 



Genus I. PHASCOLODON, Stein. 

 Animalcules free-swimming, persistent in form, truncate in front, rounded 

 or pointed posteriorly ; the dorsal region convex ; the ventral surface plane, 



