496 ORDER HOLOTRICHA. 



genus. While most usually of a brick-red hue, Claparede and Lachmann mention 

 that the colour in this species is sometimes entirely absent, while in other instances, 

 through the presence of enclosed Oscillatoriae, it assumes a brilliant glaucous hue. 



Nassula lateritia, C. & L. 



Body ovoid, cylindrical, twice as long as broad, rounded posteriorly, the 

 anterior border obliquely truncate ; pale red or rose colour ; mouth opening 

 on the truncate anterior portion; pharyngeal armature consisting of an 

 anteriorly dilated tubular fascicle of rod-like teeth ; contractile vesicles two 

 in number, spherical ; endoplast discoidal, posteriorly situated ; trichocysts 

 numerous, relatively smaller than in N. rtibens. Length 1-500". 



HAB. Pond water. 



Nassula microstoma, Cohn. 



Body persistent in shape, oblong, slightly compressed, the anterior 

 extremity bluntly rounded, the posterior one somewhat pointed ; a depressed 

 area, which conducts to the circular oral aperture, developed on one side, 

 near the anterior extremity ; pharyngeal tube obliquely directed, simple and 

 unarmed, dilated posteriorly ; endoplast subcentral, obliquely placed, having 

 an attached endoplastule ; contractile vesicle small, spherical, located at a 

 distance of one-third of the entire length of the body from the posterior 

 extremity ; surface of cuticle finely striate or furrowed longitudinally ; cilia 

 fine, set in these furrows, equally clothing the entire cuticular surface ; colour 

 flesh-red. Length 1-240". HAB. Salt water. 



Cohn * remarks that this type most nearly resembles the Prorodon marimis of 

 Claparede and Lachmann, and may possibly be identical with O. F. Miiller's Para- 

 mcerium chrysalis, or the Panophrys chrysalis or rubra of Dujardin. 



Doubtful Species. 



The Liosiphon Stromphii of Ehrenberg, separated from Nassula on account of 

 the great projection of the anterior region beyond the oral aperture, scarcely 

 appears to possess a sound claim for separate generic distinction. Its form is 

 obtusely ovate, colour green, length 1-432", hab. pond water ; the tubular pharyngeal 

 passage encloses a cylindrical or somewhat clavate fascicle of rod-like teeth, as 

 obtains among the majority of the members of the present genus. 



GENUS III. CYRTOSTOMUM, Stein. 



Animalcules ovoid or elliptical, highly contractile ; oral aperture lateral, 

 taking the form of a longitudinal cleft ; pharynx tubular, its wider anterior 

 extremity armed with two closely approximated rows of short, rod-like 

 teeth ; cilia of cuticular surface disposed in even longitudinal rows ; tricho- 

 cysts usually present. Inhabiting fresh water. , 



This genus, as founded by Stein on the Bnrsaria (Frontonia) leucas of Ehrenberg, 

 differs chiefly from Nassula in the highly elastic consistence of the cuticular invest- 

 ment, which allows the animalcules to assume a variety of polymorphic contours. 



* " Neue Infusorien im Seeaquarium," ' Zeitschrift fur Wissenschaftliche Zoologie,' Bd. xvi. 

 1866. 



