466 ORDER CILIO-FLAGELLATA. 



Divested of their flagellate appendages, the as yet but little known representatives 

 of this small family group would bear a marked resemblance to such free Peritricha 

 as Strombid'nnn and Halteria, and it is not improbable that the transition or line of 

 evolution from the Flagellata to the above-named group of the Ciliata is accom- 

 plished in this direction. 



GENUS I. STEPHANOMONAS, S. K. 



Animalcules free-swimming, more or less ovate, bearing a crown or 

 wreath of cilia at the anterior extremity of the body, from the centre 

 of which a single persistent flagellum takes its origin ; the remaining 

 surface of the cuticle entirely smooth. 



This genus is instituted for the form referred with some doubt by De Fromentel * 

 to the genus Trichomonas under the title of T. locellus ; the symmetrical, crown- 

 like disposal of the cilia and single flagellate appendage at the anterior end of the 

 body serve at once, however, to distinguish it from all the members of that generic 

 group. It is possible that the Asthmatos ciliaris of Salisbury is identical with, or 

 closely allied to this same form, though in that type both the flagellum and cilia 

 appear to be much more fugacious in character. 



Stephanomonas locellus, From. sp. PL. XXIV. FIG. 69. 



Body ovate or pyriform, truncate and slightly narrower anteriorly ; 

 about twice as long as broad, the posterior region rounded and inflated ; 

 ciliary wreath symmetrical, encircling the anterior border ; flagellum thickest 

 towards the base, scarcely exceeding the length of the body ; endoplasm 

 transparent, granular. Length 1-800". HAB. Fresh water. 



This species, as above intimated, is identical with the Trichomonas locellus of 

 De Fromentel. The Trichomonas minima of the same writer, somewhat resembling 

 the present form, but of apparently considerably smaller size, and in which the 

 central flagellum was not distinctly observed, represents possibly a second species 

 of the genus Stephanomonas. De Fromentel's Trichomonas hirsuta, with non-vibratile 

 cilia clothing the entire cuticular surface, is apparently more closely related to his 

 own Trichomma hirsuta, presently described. 



GENUS II. ASTHMATOS, Salisbury. 



Animalcules free-swimming, ovate or spherical, bearing a terminal crest 

 or brush-like fascicle of long, vibratile, retractile cilia, which is supplemented 

 by a central, long, extensile flagellum or proboscis-like process ; the 

 remaining cuticular surface naked, soft and plastic, permitting the body to 

 assume various outlines. 



The aspect of the as yet single known species of this genus, as described and 

 figured by Dr. Salisbury in Hallier's ' Zeitschrift fur Parisitenkunde,' Bd. iv. 1873, 

 conforms so closely, when the flagellum or so-called proboscis is retracted, with such 

 Ciliata as Strombidium or Mesodinium, that it was at first proposed to refer the type 

 to the Peritrichous order. The supplementary appendage named, however, agrees 

 so essentially in nature with that of an ordinary but somewhat thickened flagellum, 

 and the cilia themselves possess in their retractile capacity so distinct and it may be 



* ' Etudes sur les Microzoaires,' Paris, 1876. 



