GENUS ENTOSIPHON. 437 



refringent ovate body, apparently the endoplast, was detected in one example 

 close to the centre of the left-hand border, and a clear vacuolar space near the 

 posterior extremity, which may have been the contractile vesicle, and which would 

 in that case be situated in a position precisely opposite to that of the previously 

 described species. Mingled with the ordinary forms, smaller flattened ovate 

 zooids, attached by the pointed anterior end by a long anchoring flagellum, and 

 having as yet no second vibratile one, were observed ; these, as delineated at 

 PI. XXIV. Fig. 38, apparently represented an earlier and larval condition of the 

 adult individuals, though their growth to the same has yet to be determined. As 

 shown in the account given of Heteromita rostrata and H. uncinata, a similar mono- 

 flagellate larval condition obtains also in that isomorphic genus. 



Anisonema (?) griseolum, Perty sp. 



Body elongate-ovoid, twice as long as broad, narrower posteriorly ; 

 flagella equal, not much exceeding the body in length ; endoplasra 

 granular, greyish brown. Length 1-250". 



HAB. Pond water ; movements slow, mostly rotatory. 



This species, described and figured by Perty under the title of Dinema griseolum, 

 and referred by Diesing to the genus Heteronema, does not appear to have been 

 met with by any recent investigator. Its dimensions exceed those of any other 

 representative of the present genus yet recorded, the rotatory motion attested to by 

 Perty is also abnormal. 



Doubtful Species. 



De Fromentel * has bestowed new names on several forms included by him in 

 the genus Heteromita, held by him, in common with many other writers, to be the 

 equivalent of the genera Heteromita, Heteronema, and Anisonema of Dujardin. 

 Certain of these possibly belong to Anisonema, but are too vaguely figured and 

 described in most instances for reidentification. His Heteromita (Anisonema ?) gibbosa, 

 characterized by its oval dorsal contour and gibbous enlargement of the posterior 

 extremity as seen in profile, with a thicker trailing flagellum, equalling twice the 

 length of the body, is the only one out of these it is desirable to retain. No dimen- 

 sions or details as to habitat are given with his description, though if drawn to the 

 same scale as most of the other figures in his plate, its length would be about the 

 i-ioooth part of an inch. The Heteromita crass a of the same writer is beyond 

 doubt identical with the Anisonema acinus of Dujardin. 



The magnification of 400 diameters only, employed by De Fromentel for the 

 delineation and description of the Flagellate forms treated of in his book, is 

 altogether inadequate for their successful or even serious investigation. 



GENUS IV. ENTOSIPHON, Stein. 



Animalcules free-swimming, persistent in shape, more or less ovate, 

 usually compressed, the cuticular surface indurated ; flagella two in number, 

 the one trailing and the other vibratile, inserted close to each other near 

 the oral fossa ; oral aperture terminal, followed by a distinct tubular 

 pharynx, the walls of which are indurated and capable of protrusion in, 

 the form of a horny tube beyond the anterior margin ; endoplasm trans- 

 parent, granular ; contractile vesicle and endoplast conspicuous. Inhabiting 

 fresh water. 



This genus is founded by Stein \ on the Anisonema sulcata of Dujardin ; the. 

 essential feature distinguishing it from the ordinary members of the genus Anisonema 



* ' Etudes sur les Microzoaires,' 1876, t 'Infusionsthiere,' Abth. iii., 1878. 



