3 i2 DISCOVERY REPORTS 



anterior are pectinate and the remainder spine-setae. The proximal endite arises in the angle between 

 the limb and the body. The ventral body-wall, in preserved material, usually bulges downwards 

 between the proximal endites of the two sides, but is provided with muscles radiating to it from the 

 anterior hypostomal apodeme. It would appear probable that this muscular system is used in conjunc- 

 tion with the labral muscle to enlarge the oral atrium. Depression of the body-wall must be by haemo- 

 coelic pressure, and flexure of the body. The middle and distal endites bear a series of powerful, 

 inwardly directed spine-setae. The anterior spine-setae are pectinate with their secondary teeth 

 apically directed. Skogsberg referred to the movable articulation between the articles of the protopod 

 and their well-developed independent musculature. He also pointed out that the endites are not 

 movable in relation to the articles from which they arise. Independent movement of the proximal 



0-1 mm 



Fig. 9. C. borealis antipoda. Right maxillula from inside, b, basis; c, coxa; e« 1 , first article of endopod; 



en 2 , second article of endopod; p.c, pre-coxa. 



articles is great, but may be analyzed into two main components. One movement of each is rotation 

 with respect to the length of the limb, thus swinging its endite through a horizontal arc. The other is 

 a rocking movement which swings the endite through a small vertical arc. Skogsberg pointed out the 

 marked divergence of the direction of the endites with the limb at rest. He did not, however, point 

 out their range of movement or their relation to the other appendages. The proximal (pre-coxal) 

 endites may be more or less directed towards one another across the body when its floor is raised. More 

 usually they are directed forward between the paragnaths toward the incisor edges of the mandibular 

 coxae; then the floor of the body is usually depressed. By an anterior rocking of the limb, their setae 

 are thrust forward and upward between the molar spines of the mandibular coxae, their proximal 

 brush-setae extending almost to the mouth. The coxa can move relative to the pre-coxa but the 

 positions of its endites will also depend upon movements of the latter. The total range of movement 

 of the coxal endites would seem to be from a position where they point straight across the body to one 

 in which they point somewhat forwards and inwards between the mandibular gnathobases. They may 

 be depressed to a position pointing slightly ventrally to the gnathobase of the mandibular basis or 

 elevated so that they point towards the incisor surfaces of the coxa of this limb. 



The palp of the maxillula (Fig. 2, Fig. 7 mx-^p, Fig. 9) is generally accepted to be the endopod, but 

 the basipod, which is very short and bears no endite is, as Hansen (1925) pointed out, partly fused with 

 the first article of the endopod. The second article of the palp (first endopod article) is the longest of 



