Discovery reports (1962) Discovery reports discoveryreports31inst Year: 1962 3i2 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-
Discovery reports (1962) Discovery reports discoveryreports31inst Year: 1962 3i2 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; en2, second article of endopod; , 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 usual
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