18 G. O. Sars. 



organ of a claviforni shape. The frontal part of the head 

 is narrowly produced, and its obtusely rounded extremity 

 is to a great extent filled up with the large compound eyes. 

 Below the frontal part, the head exhibits a rather slight 

 sinus, and is produced behind this to a comparatively short 

 and broad, obtuse-angled rostral expansion. 



The trunk (see PI. II, fig. 3) is more than twice as 

 long as the anterior division of the body, and is extended 

 straight backwards, with a very slight curvature downwards 

 in its most posterior part. It is nearly cylindric in form, 

 only slightly tapering distally, and is divided into 20 rather 

 uniform segments, the last of which, however, is imperfectly 

 defined from the caudal part (see PL III, fig. 3). Dorsally, 

 the greater part of the segments are provided with trans- 

 verse rows of posteriorly curving spiniform bristles, which 

 successively disappear on the anterior segments. 



The caudal part (see also PI. Ill, fig. 3) is rather short 

 and slightly deflexed, containing anteriorly the terminal 

 part of the intestine, whereas posteriorly it is produced to 

 2 juxtaposed, thin lamellæ, the caudal plates, separated by 

 a deep groove. These lamellæ each terminate below in a 

 very acute spiniform corner, and have their posterior edge 

 divided into 12 — 16 rather uniform, minute denticles. Between 

 the lamellæ at their uppermost part there is a small tubercle 

 carrying 2 slender ciliated bristles, the caudal setæ. Above 

 these the dorsal face of the tail forms a heel-shaped 

 convexity, which is armed with a single pair of strong, 

 posteriorly curving spines. At the end in front, the 

 caudal part is produced to two small, juxtaposed, dentiform 

 projections, and immediately behind them the caudal claws 

 are movablv articulated to the tip of the tail. These claws 

 are rather strong, somewhat exceeding the length of the 



