158 M. HARTOG ON FEEDING OF PHYLLOPODS AND CLADOCERA. 



suspension as they pass back drift into the angle where the 

 hinder end of the body bends abruptly down. Here they are 

 turned forward into a reverse eddy, forwards, under and along 

 the median line of the body, till they reach the oral region 

 behind the labrum, where the play of the mandibles, like that of 

 Apus, sends them into the gullet to be swallowed. If the solids 

 in the water be in excess, the accumulation against the labrum 

 is too large to be dealt with in this way ; and the hinder end of 

 the body, armed as it is with two strong spines, is, as it were, 

 scraped along the median groove, and turned sharply downwards 

 and backwards at the end of the stroke, so as to scoop away 

 the clogging mass and expel it from the shell. I may note that 

 by adding carmine to the water we can see that the food passes 

 freely from the gut proper into the pyloric caeca, which are 

 therefore not merely secreting organs. 



They may often be seen feeding in this way when resting by 

 the back of the head against a weed or the wall of the vessel. 

 A large sensory nerve ends here, and possibly the end organ 

 may secrete matter viscid enough to fix the animal, so long as 

 it does not execute vigorous swimming movements. This " dorsal 

 organ " (or rather " nuchal organ ") is especially well developed 

 in Sida. 



While the general rhythm of the bulk of the limbs of Crustacea 

 is backwards, their bases and their epipodial appendages tend to 

 work in the reverse direction. This is especially visible in the 

 last gill of Daphnia^ and is notably the case with the gills, etc., of 

 the Decapoda, the highest group. 



The Nauplius larva of Cyclops has a so-called " masticatory 

 hook " at the base of its second pair of appendages, which works 

 into the pharynx just in the same way as do the mandibles of 

 Apus or DapJinia. 



Journ Quekett Microscopical Club, Ser. 2, Vol. VJIL, No. 49, November 1001. 



