316 DISCOVERY REPORTS 



Besides the antero-posterior movement of the shaft of the maxilla, the exopod is capable of similar 

 movement. In preserved material it usually lies parallel to the margin of the shell, with its terminal 

 claws directed straight back. It may, however, be flexed ventrally to produce a curvature of the limb, 

 while the terminal article may be flexed so far that the claws are directed vertically downwards at right 

 angles to the remainder of the limb. Professor A. C. Hardy has pointed out to me, in a personal 

 communication, that the live animal quite normally extends the whole limb vertically downwards. 

 Such a movement will draw the ventral setae and terminal claws forward along the ventral posterior 

 margin of the carapace and bring the whole maxilla within reach of the inward arc of movement of 

 the mandibular claws. 



Fig. 1 2. C. borealis antipoda. A, female right first trunk limb from inside ; B, apex of the same appendage in male. 



ep, epipod; ex, exopod; p, protopod. 



With its wide range of antero-posterior movement and ventrally curved terminal claws, the 

 elongate exopod of the maxillae may play some part in collection of food. The short endopods, with 

 posteriorly curving claws, probably play a main role in food transport in conjunction with the 

 maxillulary palps. The endites, as described above, are very poorly developed. Their long slender 

 brush-setae may assist in forward transport of fine food-material, but can be of little use for manipula- 

 tion of larger material. Marginal setae of the exopod may aid retention of food-material. 



The epipod of this appendage, in conjunction with that of the first trunk-limb, undoubtedly creates a 

 respiratory water-current through the carapace in a manner similar to that in Cypridopsis ( = Piotiocypris 

 vidua) and in Cypridina described by Graham Cannon (1926, 1931). Miiller (1894) had in fact 

 observed this current in Conchoecia experimentally with the aid of carmine particles. He also described 

 how the epipods beat continuously and independently of other movements of the limbs. 



First trunk-limbs 



The first trunk-limbs are uniramous, jointed and pediform. The protopod bears a well-developed 

 epipod. They show sexual dimorphism. Though very similar in general appearance to the maxillae, 

 as pointed out by Skogsberg (1920), their endopods are even less well developed. The protopod of 

 each arises immediately behind that of the maxilla so that it extends ventrally below the posterior 

 extreme of the isthmus linking the body of the animal with the carapace. It bears an epipod similar 

 to that of the maxilla. As might be expected from its position in relation to the protopod of the 



