498 



SYSTEMATIC HISTOEY OF THE INFUSORIA. 



motion. I have not unfrequently Tvdtnessed the transition of Monads to the 

 condition of Cercomonads. 



We may conclude that many of the animalcules described in the genus 

 Bodo (Ehr.) are examples of this genus {Cercomonas, Duj.), although suffi- 

 ciently marked characters are wanting in order to discover specific identity. 



Cercomonas detracta. — Discoid or 

 oblong, granular, with a thick tail. 

 1-7000" to 1-2300". 



C. crassicauda. — Elongated^ nodular, 

 flexible, or variable in fonn, more or 

 less contracted posteriorly into a tail. 

 1-3400" to 1-2600". 



C. viridis. — Ovoid, oblong, tubercular, 

 green, prolonged posteriorly into a tail 

 of varying tenuity, or into a rounded 

 lobe or spathulate expansion. 1-1500". 

 Perty believes this to be no other than 

 an early stage of development of Euglena 

 viridis. 



C. lacryma. — Globular, imequal, elon- 

 gated posteriorlv as a long flexuose tail. 

 Length of body 1-5200" to 1-3000" ; of 

 tail 1-2600''; of filament 1-750". 



C. acuminata (xviii. 20). — Globular or 

 ovoid, contracted posteriorly into a short 

 tail, temiinated bv a veiy fine filament. 

 1-2600" to 1-1900". 



C. Globulus (xyju. 23). — Globular, 

 with a filament at each extremity double 

 its length, the anterior one more actively 



moved. Length 1-2600". In marsh- 

 water. 



C. longicauda (xvin, 22). — Fusiform, 

 flexible, terminated posteriorly by a long 

 and very slender flexuose filament. 

 1-1800". 



C. fusiformis. — Dilated at centi'e, con- 

 stricted in front, and prolonged behind 

 into a long delicate tail. Length of body 

 1-1900". 



C. cylindrica. — Elongated, cylindri- 

 cal, constricted posteriorly, terminated 

 by a long, straight, and very thin tail. 

 Length of body 1-2600"; of tail the same. 



C. truncata (xviii. 12 a, h). — Con- 

 tracted posteriorly; truncate in front, 

 with a filament springing from each of 

 the trimcated angles ; the posterior 

 angle extended more or less into a 

 lobe. 1-3000" to 1-1900". 



C. lohata (xvin. 11 a, b). — Variable in 

 form, tubercular, sending out a flageUi- 

 form filament from the end of an ante- 

 rior lobe, and emitting also one or two 

 other lobes. 1-3250" to 2-3250". 



It is right to mention that Dujardin has noted the occuiTence of several of 

 the above Cercomonads in organic infusions, in conjunction particularly with 

 Monas Lens, and that he inclines to the idea that these differently-named In- 

 fusoria are merely diff'erent conditions of the same animalcule. 



Perty adds the following species : — 



C. intestinalis. — Has a posterior vi- 

 brating filament, and probably an ante- 

 rior one also. Internal molecules very 

 fine ; body transparent ; posterior fila- 

 ment about three times the length of the 

 body. Is common in the intestine of the 

 frog, and is in part equivalent to Bodo 

 intestinalis (E.). 1-3000". 



C. curvata. — Cylindrical, curved, with 

 an anterior and a posterior filament. In 

 some specimens apparently two fila- 

 ments occurred in front. 1-2400". Very 

 active : occurs among the ova of the 

 frog {Bana temporaria). 



C. vorticellaris= Bodo socialis and B. 

 voi'ticellaris (E.). 



C. Ra7iarum=Bodoranarum ? (E.). — 

 Colourless, soft, more or less conical ; 

 tapering or roimded behind, but without 

 posterior filament. In water with Mol- 

 lusca, and in the intestine of frogs. 



C. clavata. — Colourless or greyish, 

 thickened anteriorly, tapering poste- 

 riorly, club-shaped ; motion rather 

 quick; periphery clearer than the 

 centre. 1-570". 



C. Falcula. — Colom^less, ti'ansparent, 

 compressed and curved (?), much 

 widened in front, truncate and emar- 

 ginate ; posterior portion tapering to 

 a blunt apex ; movements sluggish. 

 1-720". 



Genus AMPHIMONAS (Duj.) (XVIII. 13).— Animals of variable, irre- 

 gular form, having at least two filaments, of which one is either in front, and 

 the other on one side, owing to a constriction of the body, or both are lateral, 

 and accompanied or not mth a caudiform prolongation. The leaping move- 

 ments of A. caudata are remarkable, and the variability in form is charac- 

 teristic of each species. 



