72 THE VOYAGE OF H.M.S. CHALLENGER. 



The head is rounded and convex dorsally ; the insertions of the antenna; and 

 antennules are so close together that there is only a very narrow interval of communica- 

 tion between the frontal region of the head and the posterior region ; this is also 

 characteristic of Eurycope sarsii and other species. 



The frontal margin is slightly convex, the lateral region of the bead is quadrangular 

 in shape, and is prolonged downwards and forwards for BOlne way below the attachment 

 of the thoracic limbs. 



The first segment of the thorax is very short (antero-posteriorly), and not wider than 

 the head ; its anterior margin is formed of two concave areas, and the median triangular 

 process resulting from the union of these fits into a corresponding cavity in the posterior 

 margin of the head ; laterally the segment lies completely parallel to the lateral region 

 of the head, and is slightly overlapped in the way shown in the figure (PI. XIV. fig. l) 

 by the second segment of the thorax ; its appendage is attached at a point considerably 

 below the level of the succeeding appendages of the thorax. 



The second and third segments of the thorax are subequal and slightly longer than 

 the first segment ; each is ridged anteriorly and posteriorly, the central area of the 

 segment being depressed and saddle-shaped ; laterally each of the segments is occupied by 

 an oval convexity, which is larger in the third than in the second segment. The second 

 segment has a concave anterior and a convex posterior margin, the lines being almost 

 straight in the middle of the segment. The third segment is concave anteriorly, but its 

 posterior margin is concave in the middle and convex laterally. 



The fourth segment of the thorax- is as long as the second and third taken together, 

 it is on the whole similar to those, but the lateral convex areas are larger. The curvature 

 of the anterior and posterior margins are parallel to each other and to the posterior 

 boundary of the segment in front. 



All these segments are furnished with short epimera. 



The width of the body is greatest at the fourth segment. 



The length of the first four segments of the thorax taken together is 5 mm.; the 

 three posterior segments of the thorax measure together 18 mm. 



The fifth segment of the thorax is V-shaped, but not so strikingly so as in many 

 allied species, among others Munnop>sis sarsii; the concave posterior boundary of the 

 segment is much less deeply curved than the anterior convexity ; the upper surface of 

 the segment is very convex and is traversed by a longitudinal median furrow which 

 divides it into two areas. 



The sixth segment is of approximately the same shape and size as the preceding one. 



The seventh segment is distinctly shorter; its anterior and posterior margins are 

 parallel with each other and almost straight. 



The epimera of these segments are very short and inconspicuous. 



As may be seen in the figure (PI. XIV. fig. 1) the limbs belonging to these segments 



