the particles are to be masticated. The teeth, the rectangular lobe, and the feather- 

 like bristles together with those from the opposite mandibl.e encircle a space and 

 cause every particle swept down into the lower part of the buccal cavity by the 

 combing teeth and the fringe to be caught within this space from which it is not 

 able to escape. 



The maxillae are large flattened plates; they are not of such a complicated 

 structure as the mandibles, but as to form and equipment with hairs they differ in 

 the different species more than the mandibles. They are often roughly conical, 

 longer than broad, but may also, as in T. annulata, be broader than long. They are 

 furnished with a longitudinal suture, and carry outwardly a small basal appendage, 

 generally indicated as palpe. In all these species, which find their food in the water 

 layers, living on. suspended material, the apex of the maxillae carries a long thick 

 tuft of hairs; these hairs may be feathered as in C. pipiens and nigritulus; the same 

 tuft may also be long in most of the species which partly seek their food on 

 the bottom; still the tuft here is never so well developed, consisting as it does of 

 shorter hairs ; it may as in T. annulata be wholly absent. On the inner edge of the 

 maxillae is commonly inserted a series of long stiff hairs, and the whole space 

 between the above-named suture and the inner margin is covered with a coating of 

 long, soft hairs, now and then arranged in bands (C. pipiens and nigritulus). In 

 F. geniculata the whole upper and inner part of the maxillae are covered with a fel- 

 ted coating of very short hairs; outside the terminal brush is inserted a thorn-like 

 hair, very conspicuous in Tceniorhynchus. The palpe bears on its top four or five, 

 little digit-like prolongations undoubtedly of sensory function. The maxillae cover 

 the mouth from beneath; they are but slightly movable; when the catch- or brush 

 apparatus of the labrum is not used, it is folded in, and the large maxillae form 

 the floor of the space, in which the labrum and the other mouth-parts are concealed. 

 When the brushes are to be unfolded, the maxillae are unclapped, then the brushes 

 appear, and a moment later these begin to act. During the movement of the fla- 

 bellae the maxillae are quite immovable; together with the long apical hair-brushes 

 they border the space, in to which the particles are swept. It may further be ob- 

 served that the two maxillae never reach each other, but leave an open space be- 

 tween them; this is mostly covered by the above-named hairs along the inner 

 margin ; but lowest and nearest to the attachment of the maxillae a triangular space 

 is left hair-free. If now we direct our attention to this point on a feeding larva, 

 we shall be able to see that an irregular row of small pellets passes through this 

 little cleft. The pellets do not come at regular intervals, but irregularly, now and 

 then in long chains. These pellets represent all the material swept down into the 

 buccal cavity, which the larvae are unable to use. We therefore see that these 

 larvae too are able to select out of the captured material what they wish to use; 

 as, by means of the binoculary aquarium microscope, we are able to observe those 

 pellets which pass the oesophagus and the swallowing movements during the feed- 

 ing process, I have also noticed that there are periods in which all material, caught 



