5o8 ORDER HOLOTRICHA. 



In their brief description and illustration of this type, Claparede and Lach- 

 mann mention that the rugose induration of the cuticular surface does not extend 

 quite to the posterior extremity of the body, but leaves a short, soft, terminal portion 

 exposed. This species was originally obtained by M. Lachmann at Glesnoes, on 

 the Norwegian coast. 



Coleps incurvus, Ehr. 



Body oblong, subcylindrical, slightly curved, terminating posteriorly in 

 five points. Length 1-430". Hab.— Fresh water, among ConfervcB. 



Coleps amphacantlius, Ehr. 



Body shortly ovate, cuticular surface divided by transverse furrows into 

 numerous annular indurated segments, the anterior margin unequally den- 

 ticulate, three strong spines or cusps at the posterior extremity. Length 

 1-280". Hab. — Fresh water. 



Genus II. PLAGIOPOGON, Stein. 



Animalcules free-swimming, persistent in shape, oval, subcylindrical, 

 longitudinally furrowed ; oral aperture anteriorly situated, surrounded by a 

 circle of stiff setose cilia ; fine, hair-like, vibratile cilia clothing the remain- 

 ing cuticular surface ; no apical or posterior spines ; contractile vesicle and 

 anal aperture posteriorly located. 



Plagiopogon coleps, Stein. Pl. XXVII. Fig. 7. 



Body ovate, subcylindrical, a little over twice as long as broad, longi- 

 tudinal furrows rather widely separated, the intervening spaces finely striate 

 transversely. Length 1-300". Hab. — Salt and fresh water. 



This typical species of the genus Plagiopogon is founded by Stein * upon the 

 Holophrya coleps of Ehrenberg and the Coleps inermis of Perty. As delineated by 

 these two authorities, the animalcule resembles a Coleps hirtus devoid of posterior 

 spines, and having its surface furrowed in a longitudinal direction only. 



Genus III. POLYKRIKOS, Biitschli. 



Animalcules free-swimming, persistent in shape, subcylindrical or barrel- 

 shaped ; oral aperture terminal, having issuing from it a long bristle- 

 like seta ; numerous annular shortly ciliate grooves transversely encircling 

 the body ; cndoplasm enclosing irregularly disposed trichocysts (.''). 



Polykrikos Schwartzii, Biitschli. Pl. XXVII. Figs. 8-10. 



Body barrel-shaped, subcylindrical, slightly narrowed and truncate at 

 the two extremities, about twice as long as broad ; transverse ciliary zones, 

 eight to twelve or more in number, converging forwards on one side so as to 

 form an obtuse angle parallel with the projection of the succeeding ring ; the 

 border of the oral aperture four-lobed ; a long stiff seta, similar to the oral 

 one, produced obliquely forwards from the body at a distance of about 



* 'Prager Lotos,' Bd. ix,, 1859. 



