30 M. F. DUNLOP ON A NEW ROTIFER, CATHYPNA LIGONA. 



did not hjirmonise with certain other appearances, and after 

 considerable trouble I found that the appendage was a pro- 

 longation of the ventral plate beyond the termination of the 

 dorsal plate. In the course of observing, great help was 

 obtained from a little vorticella which adhered to an empty 

 lorica, and which in swimming about dragged the lorica against 

 obstructions here and there, causing it to be canted in all 

 directions and affording various views which enabled a pretty 

 eood notion of the structure to be obtained in an easier manner 

 than with the aid of a needle, however fine. 



The lorica of the new species is somewhat depressed, thicker 

 behind than in front, and consists of two plates apparently 

 joined together by a flexible membrane which forms a sulcus- 

 or furrow both longitudinally and at the rear. 



The ventral 2)late is broader and longer than the dorsal, and 

 has a peculiar posterior prolongation or appendage slightly arched 

 in the centre. 



The toes are two, short and blade-shaped, with a slight trace 

 of shouldering on their outer margins. 



An idea of the form of the animal may probably be best 

 obtained from a description of an empty lorica, view^ed from 

 above. The mental edge is slightly concave, and in wddth is 

 about five-eighths of the whole length of the lorica. The 

 lateral edge on either side gently and gradually swells out for 

 about two-thirds of its length, when it curves inwardly, and 

 then abruptly turns out for about one-eighth of its whole 

 length, when a sinuous line slightly convex in the centre joins 

 both sides. The occipital edge is convex. The lateral edges 

 of the dorsal plate do not quite extend to the lateral edges of 

 the ventral plate, which is increasingly broader posteriorly, and 

 about the point where the outline of the ventral plate abruptly 

 turns out, the dorsal plate is terminated by a nearly straight 

 line. An inner lateral line on either side appears to indicate 

 the inner edge of the inangulation. The internal anatomy 

 is quite normal. The trophi have the mallei well developed, 

 and I should say are virgate. I was unable satisfactorily to 

 make out an eye or eyes. The foot projects through a squarish 

 opening in the ventral plate, and when the animal is swimming 

 the toes are trailed behind, but w^hen feeding it poises on the 



