HiLGENDOKF. — Oil Nctv Zealand Kotifera. 119 



the right side of the animal, and extends through nearly a 

 third of its length. 



Planoventer varicolor moves by swimming with its ciliary 

 wreath. Its motions are slow, deliberate, and steady. It 

 never retracts any part of its body, and so affords great facili- 

 ties for observation. The extrusion of its jaws has been 

 mentioned. This is not an uncommon movement. On one 

 occasion I saw it put out its jaws and seize the end of a 

 piece of Alga, draw it into its mouth, then shift its hold with 

 the troplii, and draw it still further into its mouth, and so on 

 until the piece of Alga stretched unbroken through the whole 

 length of the stomach. Then it was cut off by the ever-active 

 jaws. 



Hah. The pool. 



Sometimes common, and again not seen for weeks. 



Sub-order LOEICATA. 



Family Eattulid^. 



Genus Mastigocerca, Ehrenberg. 



Generic characteristics : Body fusiform, or irregularly 

 thick. Toe a single style, with accessory stylets at its base. 

 Lorica often furnished with a thin dorsal ridge. 



VI. Mastigocerca flectocaudatus, sp. nov. Plate VIII., fig. vi. 



Specific characters : Body compressed, flat ventrally, arched 

 dorsally, and bent down anteriorly. There is no dorsal ridge. 

 There is a long toe, nearly as long as the body, and a single 

 long substyle, two-thirds as long as the toe. Cervical eye. 



No colour except what is caused by highly refractive brown 

 cells in the walls of the stomach. This Rotifer almost in- 

 variably swims on its side, and so a side view is by far the 

 most familiar. It is more than three times as long as it is 

 high, and the outline of the body is made up of long curves. 

 The height is probably greater than the breadth, since the 

 usual position in swimming under the cover-glass is on the 

 side. This fact, however, may be explained by the bend in 

 the foot, to be described now. The foot proper is very short 

 and indistinct, but bears a very long style and a shorter sub- 

 style, which are bent downwards, and which are incapable of 

 being straightened ; moreover, they are set in the foot with a 

 downward inclination, and so always have a general direction 

 at about right angles to the body. This fact would account 

 for the Eotifer not swimming on its ventral surface when 

 under the pressure of the glass. The style is more than two- 

 thirds as long as the body and head of the Eotifer, while the 

 substyle is two-thirds as long as the main style. The foot is 

 often bent so that the tip of the style touches the anterior 



