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cilia in like manner (fig. 1, e, e). The appearance is now not unlike 

 that of a flower of four unequal petals ; from which resemblance, Lin- 

 nreus, who compared it to a ringent, labiate corolla, gave it the trivial 

 name ringens, by which it is still known. On each petal we see a 

 white line, probably a nervous thread, running parallel with the 

 margin, to which many short lines radiate from it. 



But the eye is involuntarily drawn from the petals themselves of 

 this living flower, to the beauty of the coursing cilia (fig. 1,/,/) : these 

 appear to chase each other in ceaseless race along the margin, running 

 down and up the sinuous divisions of the petals, now relaxing, now 

 refreshing, their speed. This progression of the ciliary waves is now 

 explained ; but while we gaze upon them, we find it easy to forgive 

 the error of Colombo and Dutrochet, who maintained that the teeth 

 actually ran around the margin of the stationary wheel. There is a 

 remarkable phenomenon in the ciliary course in this genus, which I 

 have observed also to characterize Limnias, Megalotrocha, and a 

 species which has occurred to me, belonging to an undescribed genus ; 

 but which does not occur to nearly the same extent in the Rotifera 

 generally. Each cilium appears thickened in one or two places in a 

 very regular manner, forming thick black spots, which run along the 

 course, and produce a very striking effect. I conjecture that each 

 cilium is alternately either dilated and attenuated, or else bent nearly 

 in the line of vision at these points (so as to appear thick by perspec- 

 tive), and straightened, in rapid succession. 



Below the large petals on the ventral aspect, and just above the 

 level of the projecting respiratory tubes, is a small circular disk, or 

 aperture, within the margin of which a rapid rotation goes on (fig. 1, 

 g). This little organ, which seems to have hitherto escaped obser- 

 vation, I can compare to nothing so well as to one of these little 

 circular ventilators, which we sometimes see in one of the upper 

 panes of a kitchen-window, running round and round, for the cure of 

 smoky chimneys. 



The gizzard, or muscular bulb of the oesophagus (fig. 1, h), is 

 always very distinct, and its structure is readily demonstrated. It 

 consists of two sub -hemispherical portions, or jaws, each of which is 

 crossed by three developed teeth, which are succeeded by three or 

 four parallel lines, as if new teeth might grow from thence. The 

 teeth are straight, slender, swelling towards their extremity, and 

 pointed. These armed hemispheres work on each other, and on a 

 V-shaped, or tabuliform apparatus beneath, common to most of the 

 Rotifera, but in this genus very small. 



