NEBALIOPSIS 207 



extension backwards and flattening out of the paragnaths, the Hmb slopes obhquely 

 forwards and the tips of the setae he ahnost in a frontal plane. 



Thus the main mass of the maxilla forms a comb of setae lying close against the body 

 wall (the paragnaths) and extending some considerable distance behind the mouth. 

 The morphologically posterior face of the limb is thus ventral and will be referred to 

 as the ventral surface. The remainder of the limb projects forwards on either side of 

 the mouth underneath the maxillules (Fig. 4 A). 



The setae are closely set with fine setules on the ventral surfaces, especially so 

 at their bases. Distally the setules are spread out so that the setae appear feathered 

 at the tips (Fig. 4 A). Immediately lateral to the bases of the setae the proximal endite 

 bears a row, or rather a strip, of closely set minute setules which project ventrally across 

 the space between the maxilla and the first trunk limb (Figs. 4 A, 5 A; Thiele, 1904, 

 PI. 3, fig. 49). 



The first trunk limb, which difters markedly from the more posterior limbs, lies close 

 against the maxilla. Its posterior face is thus ventral, and the limb can be said to lie 

 close underneath the maxilla. It bears a proximal endite which corresponds closely in 

 shape and general structure with that of the maxilla. Its setae, however, are armed with 

 setules on their upper and not their lower faces, and at the base of the setae, it carries 

 a strip of closely set minute setules just as in the case of the maxilla, but again these are 

 on the upper and not on the lower surface (Figs. 4 B, 5 A). 



The endopodite consists of a lobe bearing a few powerful setae projecting forwards 

 immediately underneath the tips of the maxilla and maxillule (Fig. 4 B). The exopodite 

 projects ventrally, and, in the specimen F,. , appears to be divided into two parts — an 

 anterior lobe and a posterior flat plate armed at the edges with long setae. Directly 

 behind this posterior part and forming a functional continuity with it, is the large plate 

 which has been homologized with the epipodites of the other trunk limbs. This is a 

 very thin plate from the edge of which project setae of approximately the same length 

 as the width of the plate. It spans completely the lateral gap between the first and 

 second trunk limbs (Fig. 3). The antero-lateral margin of the base of the limb projects 

 forwards and upwards around the side of the maxilla thus tending to close the space 

 between them (Fig. 5 A). 



The shape and arrangement of a typical trunk limb can be seen from Figs. 2 and 3. 

 It will be noticed that the limbs are all parallel to the maxilla and first trunk limb, thus 

 sloping obliquely forwards. They are wider apart anteriorly than posteriorly and the 

 inner edges of the limbs are nearer to the body wall than the outer. 



Trunk limbs 3 to 7 are closely similar in structure and are referred to as the typical 

 trunk limbs. They are unsegmented, the exopodite being represented by a slight pro- 

 jection ending in a strong spine towards the tip on the outer margin. The endopodite 

 must be considered as the tip of the limb distal to this exopodite lobe. The epipodite is 

 attached at about a third of the way up the limb and projects backwards as a very 

 slightly bilobed structure. It should be called a lobe rather than a plate, as it is com- 

 paratively thick and differs markedly in this respect and also in the fact that it bears no 



