906 SUMMAEY OF CURKENT RESEARCHES RELATING TO 



usually a single one being distally curved ; contractile vesicle single, 

 posteriorly placed ; trichocysts large and numerous. 



G. acanthocrypta, sp. nov. (Greek, akantha, spine ; Jcruptos, con- 

 cealed). Body elongate ovate, widest and rounded posteriorly, taper- 

 ing to an obtuse anterior apex, subcylindrical, slightly compressed, 

 the length twice to two and one-half times the breadth, a hemi- 

 spherical sarcode bubble usually present on the left-hand dorso-lateral 

 border ; cuticular cilia long, fine, setose, a single postero-terminal 

 Beta usually distally curved; oral aperture ciliated, remote from the 

 anterior apex, placed at the posterior termination of a shallow, 

 narrowly ovate, ciliated, adoral groove centrally and longitudinally 

 traversing three-fourths of the ventral surface, and bearing on its 

 right-hand margin a flexible comb-like appendage composed of large, 

 coarse, non-vibratile cilia, thickened distally and diminishing in 

 length as they approach the oral aperture, which they surround, the 

 adoral groove also bearing near its left-hand margin a row of long, 

 fine, vibratile hairs, and throughout its entire length a series of long 

 vibratile cilia, somewhat fascicled anteriorly, and shortening as they 

 approach the mouth; contractile vesicle single, subterminally 

 located near the right border ; nucleus ovate, mesially placed in the 

 anterior body-half ; trichocysts large, straight, apparently prismatic,, 

 tapering to an obtuse point, and bearing distally two or more minute, 

 radiating, linear processes. Length of body 1/1000 in. 



The author thus deals with the question of reproduction : — " That 

 reproduction is by transverse fission goes without saying. But if only 

 that, imagine, if you can, what becomes of all the complex ciliary 

 arrangement about the oral region. The creature to be fashioned 

 from the posterior half of the mature body must have not only a 

 ciliated adoral sinus, and the comb-like appendage, all of which 

 simple division crosswise would give, but it must somehow obtain 

 that ciliary fascicle at the anterior apex of that sinus. The posterior 

 termination of the old Ciedoctema' s groove has no such tuft to give 

 the new creature, and the latter cannot, at least does not, exude sar- 

 code filaments that shall stiffen into cilia. Then, when and how ? 

 Oh, it is so simple and so easy when it is once thought of I But no 

 one ever would think of it without seeing it. 



It is in this way. The cilia of that comb deliberately unite 

 laterally and form a membrane. The anterior cilia of the sinus 

 unite with it and lengthen the membrane to the front, the newly- 

 formed tissue being widest somewhat in advance of its centre, and 

 narrowing toward both ends. The animal then separates across the 

 middle, forming two Holotrichous creatures, each with a perfectly 

 smooth, unwrinkled membrane vibrating somewhat obliquely along 

 the centre of its ventral surface, the free edge of this tip-tilting tissue 

 being distinctly and strongly thickened. What scheme of classifica- 

 tion has a place for them now ? If they and the systematist should 

 have a temporary encounter, what would he do with them ? Would 

 each be a fresh-water Lemhus? Such questions give them no trouble. 

 They at once proceed to form their ciliary appendages by splitting 

 up their membrane to suit. The fringes unite to form the membrane, 



