1885.] 



MICROSCOPICAL JOURNAL. 



189 



possessed by both, of withdrawing 

 the entire fascicle of tentacles at one 

 time. In A. tubcrosas however, ihe 

 tentacles do not possess the external 

 spiral ridge-like film often visible in 

 A. JluviatiHs. The latter may very 

 justly be considered the fresh-water 

 representative of the marine type. 

 From A. lemnariini it is recogniza- 

 ble chiefly by the short pedicel, the 

 posterior adhesion to the lorica, and 

 especially by the presence of but a 

 single contractile vesicle. 



The lorica walls are often seen to 

 be variously indented, bent and folded, 

 the entire lorica being often reversed 

 or inclined either by contact with 

 RotifertB or other comparatively large 

 denizens of its habitat, or by the ne- 

 cessarv manipulations.of the observer. 

 Occasionally a portion of the soft 

 body exudes through the apei"tures 

 at the antero-lateral angles, thus lift- 

 ing the extended tentacles for some 

 distance beyond the w dls ; in a single 

 instance a fascicle was entirely with- 

 drawn and an irregul ir, curved pro- 

 cess of sarcode was extruded from 

 the tentacular orifice initil its length 

 equalled that of the entire infusorian, 

 its shape and position slowly chang- 

 ing, a few minute, vesicles appearing 

 in it, but until I was compelled to 

 leave the microscope no further altera- 

 tions took place. The next morning 

 the extruded part had been partially 

 withdrawn, but the creature was 

 weakened by prolonged confinement 

 and the tentacles were not protruded. 

 The act may have been induced by 

 the discomforts of extended imprison- 

 ment and the consequent diminution 

 of the oxygen supply. 



The spiral film external to the 

 tentacles is not always present. It 

 is most frequently developed during 

 the withdrawal or partial extension 

 of the tentacle, when it is thrown 

 into irregular, closely approximated 

 ridges, the full extension of the organ 

 elongating the spirals until they be- 

 come merged into its substance. 



At the systole of the contractile 

 vesicle a narrow channel very fre- 



quently becomes visible leading from 

 the vacuole to the distal border of the 

 zooid. 



Achieta lappacca. sp. nov. (Fig. 



Lorica hyaline, subspherical, the 

 borders projecting outwardly in nu- 

 merous, conspicuous, irregularly dis- 

 tributed tubuli through which issue 

 the fine tentacles ; pedicel slender, 

 often flexuous, two to three times as 

 long as the lorica ; enclosed body 

 sub-globose, not attached to the lorica 

 posteriorly ; nucleus small, spherical, 

 subcentral ; contractile vesicles seve- 

 I'al, small, scattered. Diameter of 

 the lorica y^Vo ^^ t"9'o"o i"*^^"* ' of the en- 

 closed zooid 7^Vo ^^^'^^ ' length of 

 pedicel -<f\-^ to -^^ inch. Habitat. — 

 Fond water ; on rootlets of Lemna 

 and on Riccia Jliiitaiis. 



This approaches more nearly to 

 A. stellata, S. K. than to any other 

 member of the genus, differing from 

 it in the greatly increased length of 

 the pedicel, and in the multiple con- 

 tractile vesicles. The tentacles are 

 very fine, but exhibit conspicuous, 

 irregular protoplasmic thickenings. 

 Their length is often twice the diame- 

 ter of the lorica. They vary in num- 

 ber from fourteen to eighteen or 

 more. They are apparently not 

 capitate. 



Acineta alata.. sp. nov. (Figs. 13 

 and 14). 



Lorica irregularly ovate, widest 

 centrally, the length not greatly ex- 

 ceeding the breadth, tapering ante- 

 riorly to the rounded or obtusely 

 pointed border, and posteriorly to 

 the pedicel, the walls thin, trans* 

 parent, continuous, traversed longi- 

 tudinally by from five to eight pos- 

 teriorly diverging, compressed, wing- 

 like elevations, each pierced by about 

 four ovate, equidistant, longitudinally 

 arranged apertures for the passage 

 of the fascicles ; pedicel six to eight 

 times as long as the lorica, straight 

 or slightly curved, its hollow cavity 

 continuous with that of the sheath ; 

 enclosed zooid ovoid, somewhat 

 changeable in shape, occupying the 



