120 C. F. ROUSSELET ON DIPLOIS TRIGONA. 



compressed, elongated, and narrow ; dorsal cleft narrow, parallel- 

 sided, and open throughout ; ventral plate narrow and flat, 

 separated by lateral inangulation ; toes long, narrow, of uniform 

 thickness ; eyes two, frontal and close together. 

 Size, total T £y ; without toes, ^ ; toes alone, ^o- 



Microcodides doliaris, n. sp. (PI. VII., Fig. 4.) 



This is another new Rotifer which has been discovered at one 

 of the Club's excursions to Hertford Heath on the 6th July last. 



In appearance it is very stout and plump, with a small head and 

 prone ciliated face. The integument is soft and flexible, the body 

 barrel-shaped, with the usual longitudinal and transverse muscular 

 bands. The mastax is small, and contains jaws with broad sub- 

 square-toothed rami, and broad unci with six or seven teeth and 

 stout manubria (Fig. 4a.). The oesophagus is a thin, long tube, 

 arising near the middle of the dorsal side of the mastax, and 

 leading to the stomach and intestine of usual form. The brain is 

 a stout square mass, carrying a fairly large red eye on its under 

 surface. The dorsal antenna protrudes at the apex of a very 

 obvious dorsal prominence, while the lateral antenna? are situated 

 in the lumbar regions, rather small and difficult to see. The 

 lateral canals with tags are normal ; the contractile vesicle is 

 large when fully extended ; the ovary is a rounded mass with 

 obvious germ cells. 



The foot is peculiar; it is three-jointed, fairly long, the second 

 joint with a distinct bend ventralwards, the third joint a little 

 swollen, and ending in a single, soft, pointed toe ; the foot is very 

 flexible, and moves, or rather swings, from one side to the other 

 somewhat like a pendulum. Although the toe is single there are 

 two distinct and well- developed foot glands. 



In swimming the animal moves about very leisurely, as if the 

 small ciliary wreath were too weak for the large fat body behind ; 

 young specimens are somewhat less plump round the waist. Size, 

 total T i^ in., of which the foot is about one-fourth. A mounted 

 slide of this new Rotifer will be placed in the cabinet of the Club. 



In placing this Rotifer in Bergendal's genus Microcodides I do 

 so because I really do not exactly know where to put it. Here it 

 will be in company with two other illoricate Rotifers which have the 

 common character of possessing a single toe, but differing in some 

 other important particulars. 



