320 DISCOVERY REPORTS 



But by whatever means fine material is collected, it seems that it will be massed beneath the labrum, 

 and that transport to the oral atrium must follow. It has been pointed out already that the downward 

 arc of movement of the mandibular basis brings the incisor edge backwards and upwards into line 

 with the distal endites of the maxillule. By this means the posterior spines and setae of the basal 

 gnathobases, together with the gripping action of the incisor edges, could transport food-material into 

 the path of forward-movement of these endites. By their shearing action, the basal gnathobases may at 

 the same time cut up any larger material trapped in the secretion. During the upward arc of movement 

 of the mandibular bases, the lateral combs of the labral lamina would retain material in the oral atrium. 



Though the transversely directed spines of the distal maxillulary endites could play some part in 

 trituration of food, it seems likely that this would mainly be with large material. It is possible that the 

 peculiar structure of the molar pads on the mandibular coxae is an adaptation for trituration of fine 

 material. Certainly such material, trapped in sticky secretion, would be retained between them by the 

 fringing spinules on the posterior margin of the coxal gnathobase and on the anterior borders of the 

 paragnaths. Forward thrusting of the proximal endites of the maxillules, with their brush-setae and 

 pectinate spines (Fig. 7) together with that of the few long brush-setae of the maxillary endites, would 

 all the time tend to move material forward and upward towards the mouth. Here the orally directed 

 spinules of the coxal gnathobases of the mandibles, together with the spinules on the oral wall of the 

 labrum, would finally bring food into the mouth. Peristaltic action of the oesophagus would then 

 take over. 



During the whole feeding-process, the marginal setae of the appendages must aid retention of material 

 in positions where it can be manipulated by the appropriate appendages. 



Feeding on large material 

 Despite his observations of live specimens, Midler quite clearly did not observe a Conchoecia feeding 

 on a copepod. He found the copepod remains in the stomachs of specimens and related this to 

 his observation of the way in which the animal collected the secretion of the marginal carapace 

 glands with carmine particles trapped in it. He did not take into account the size of the prey. 

 There is, then, no direct evidence that the secretion of the glands of the carapace is involved in 

 capture of copepods. A powerful swimmer such as Conchoecia should easily capture a copepod, 

 with the aid of its clawed mandibular palps. Whether the sticky secretion of the carapace glands, 

 or perhaps the labrum, aid such capture by immobilizing the prey can be determined only by 

 observation. 



Copepod remains which are found in the stomachs of halocyprids are of such size that they would 

 pass betweeen the bases of the trunk-limbs and mouth-parts. They usually show some evidence of 

 crushing. From a specimen with an almost intact copepod in its stomach, it seems likely that 

 captured prey swallowed without being broken up into smaller portions is crushed by the mouth-parts 

 just sufficiently to enable digestion to take place. The initial grasping of such prey by the mandibular 

 palps may possibly be aided by the maxillary exopods, the claws of which are apposed to those of the 

 mandibular palp. It has been pointed out already (page 309) that, during inward flexure, the man- 

 dibular palps point slightly inward and rotate appreciably about their axes. Such movement would 

 draw any prey inward and upward and press it firmly against the ventral surface of the labrum. The 

 maxillulary palps could then help to grip the prey. A ventral movement of the apices of the mandibular 

 bases will bring the shearing action of their gnathobases into play, but small prey would be moved 

 back to pass between the bases of the appendages. In this position, manipulation of the food could 

 be aided by the maxillulary palps and the maxillary endopods. Once the anterior end of the prey has 



