40 



G. 0. SAKS. 



[No. 1. 



laterally, the above-described clear borders projecting from the 

 ocellus turn inferiorly and posteriorly (see Pl. III. figs. 4, 5). 



As a rudiment of a special sense-organ may. finally.. be 

 mentioned here the small cnp-shaped depression occurring. as 

 above stated. at the dorsal edge of the head in front of the eye. 

 and apparently connected with this organ by a chitinous chord 

 (see Pl. III, fig. 5). In the present form, this part can hardly, 

 from its small size and simple structure, have any sensory func- 

 tion. But in the genus Limnetis the corresponding part is found 

 much more fully developed. constituting. as it does, a råtner 

 large depressed oval area, beset with fine hair-like bristles, or 

 eilia; and this area has also been regarded by Grube as re- 

 presenting a special sense-organ. but of what nature he does 

 not say. 



C. Digestion. 



The food of the present Phyllopod would seem to consist 

 chiefly of vegetable matter, as microscopic Algæ. Desmidiæ, Dia- 

 tomeæ and Confervæ. The contents of the intestine are generally 

 of a light-yellow hue in its anterior part, becoming gradually 

 darker posteriorly, and the excrements ejected at intervals from 

 the anal orifice are invariably dark-brownish or well-nigh black 

 in colour. The food is conveyed to the mouth by the rhythmical 

 movements of the legs, which give rise to a whirling motion, 

 whereby any small particles suspended in the surrounding water 

 are sucked betw T een the valves and brought into the narrow 

 conduit running along the ventral side of the trunk betwixt the 

 bases of the legs. The particles are here successively thrown 

 forward, chiefly by the aid of the coxal lobes of the legs, till 

 they reach the oral region, where they are partly pushed into 

 the mouth by the aid of the maxillæ, partly caught by the pro- 

 tracted labrum, and by the retraction of that part brought im- 

 mediately within the reach of the mandibles. When the animal 

 is feeding, the latter organs are found to move almost incessantly. 

 their molar surfaces being at short intervals closely applied 



