464 EVENINGS AT THE MICROSCOPE 



ble of being turned every way. These are the uncini, and 

 are evidently used as feet, the tips being applied to the 

 glass. The optical effect of the throwing about of these 

 unoini, when the place which they touch is in focus, is 

 very curious. They are rapidly moved, but without reg- 

 ularity; the tips bend as they touch the surface of the 

 glass; some of them seem to have accessory hairs, equally 

 long, but slender, proceeding from the same base. On the 

 hinder quarter of the ventral surface are several thick 

 pointed spines ; these are inflexible^ nearly straight, placed 

 side by side, but not in regular order, some reaching 

 beyond others. I have not seen these used, but they 

 commonly remain sticking out in a horizontal direction. 

 These organs are termed styles. Besides these, there are 

 three slender bristles, called setce, placed at the hinder 

 extremity, the central one in the line of the body, the 

 others radiating at an angle. These are distinguished 

 from the cilia not only by their length, but by not be- 

 ing vibratile. The motions of these animals are powerful, 

 but irregular and fitful, very much like those of the for- 

 mer species. They dart hither and thither, backward as 

 well as forward, occasionally shooting round and round in 

 a circle, with many gyrations, much like the pretty little 

 polished beetles (Gyrinus) that play in mazy dances on 

 the surface of a pool. The two extremities seem cov- 

 ered with minute pits or stipplings, but colorless; the 

 central part is occupied with yellowish granules of dif- 

 erent sizes. 



I once witnessed the dissolution of one of these animals 

 under peculiar circumstances. Two or three stems of an 

 aquatic plant had become crossed in the live-box so as to 

 form an area, into which the 8tylonychia had somehow 



