482 Transactions of the Society. 



followed by a short but conspicuous, curved pharyngeal passage ; 

 equatorial cilia not numerous, forming three girdles, those of the 

 posterior circlet furcate ; caudal hairs long, flexible, distally curved, 

 from six to eight in number, widely separated and arising from the 

 cuticular surface at some distance from the posterior border ; con- 

 tractile vesicle apparently single, spherical, in the anterior body region 

 near one lateral border ; nucleus not observed. Movements rotatory 

 on the longitudinal axis, often rapidly backward, with sudden back- 

 ward leaps. Length of body 1/1125 in. Hab. Standing pond 

 water. 



. This is undoubtedly a member of the Halteriidae of Claparede and 

 Lachmann, but it is refused admission to any described genus by the 

 presence of the setose caudal hairs springing from the posterior body 

 region. These are subequal to the body in length, flexible but non- 

 vibratile, trailing behind when the animalcule is swimming. The 

 creature, however, possesses the ability to throw them forward, and it 

 is probable that the sudden backward leaps and quick turns so often 

 made, are accomplished by the action of these posterior setae. The 

 furcate condition of the cilia composing the posterior equatorial 

 circlet is worthy of notice. The adoral cilia appear to be fimbriated.* 



* The original drawing of this animalcule has been mislaid or lost, so that a 

 figure cannot be given. 



