HiLGENDOEF. — On New Zealand Eotifera. 129 



behind the middle. Seen from above the shape is that of 

 a narrow and long, but perfectly true, ovoid, tapering 

 behind but broader in front. The foot consists of three 

 telescopic joints ; the last of these has a slightly expanded 

 distal extremity, to which the two small triangular toes are 

 attached. The two toes are usually held close to each other. 

 The length of the foot is such that when 13exed its toes 

 reach the base of the head. It is pendent from the body 

 about three-quarters or five-sixths of the way back in the 

 body. The head is of fair size, and is very freely movable 

 on the rest of the body, but is usually retracted. It has a 

 chitinous hood, narrow and hook-shaped. Its anterior edge 

 appears not as a segment of a sphere, but somewhat indented 

 in front, as in G. bicuspidatus. The outline of the front of 

 the head is irregular, there being a kind of bay taken out 

 of it above. The ciliated ai^ea is small, and confined to the 

 lower half of the front of the head. The lorica is completely 

 closed above, but has a very small median posterior and an- 

 terior slit. It is quite open below. The two valves approach 

 each other in the middle of the ventral line, and then 

 sweep away in both directions, but more rapidly anteriorly 

 than posteriorly. There is some slight appearance of 

 longitudinal ridging of the lorica. The mastax is small, 

 of the malleate type, and situated about the junction of 

 the head and body. The alimentary canal passes along 

 the dorsal central region of the body to the origin of the 

 foot. No brain or eye was visible. Two small bright spots, 

 referred to by Ehrenberg as inexplicable, and by Gosse as 

 vesicles of air or oil, lie one on each side of the centre 

 of the middle line, near the dorsal side. Under these lie the 

 large paired reproductive organs. 



The movements are active but steady. The frontal hook 

 moves slightly, and as the point of vision is altered its anterior 

 edge appears either straight, curved convexly, or indented in 

 the middle, this last probably being the true shape. There 

 are fairly long periods of foot-anchored rest. 



Hab. In the small pool. 



Bare. 



Genus Metopidia, Ehrenberg. 



Generic characteristics : Lorica usually depressed, entire, 

 with an opening at each end for the emission of the head and 

 foot. Frontal hood in form of a hook. Foot permanently 

 extruded, of distinct joints, terminated by two furcate toes. 



XIV. Metopidia acumiiiata, Ehrenberg. Plate XI., fig. xiv. 



Specific characters : Lorica ovate, ending behind in an acute 

 point, occipitally deeply notched between projecting spines, 

 the edges very thin. 

 9 



