CRUSTACEA MALACOSTRACA. 



97 



The eyes (o) are seen along the hinder portion of the lateral margins of the projecting part of the 

 head. Each eye is a short plate, ca. 3 times as broad as long with the concave terminal margin 

 looking obliquely forwards and outwards, and its posterior corner especially is much produced out- 

 wards (fig. 4 a); any trace of visual elements is quite lacking. — The peduncle of the antennuljE is a 

 little shorter and distally a trifle thicker in the males than in the females; in the female (fig. 4 c) the 

 three joints decrease slightly in length from behind forwards whilst in the male (fig. 4 b) the two 

 distal joints are of equal length. In both sexes the outer flagellum seems but slightly longer than 

 the inner one (I have not seen adult specimens with both flagella quite unbroken), and both are fairly 

 short; in the female both flagella are almost of equal thickness, whilst in the male (fig. 4 b) the 13 

 proximal joints of the upper, outer flagellum form an extremely thickened portion the distal third 

 of which, however, tapers evenly towards the end. — The squama is between 5 and 6 times as 

 long as broad, tapering outwards with rounded apex, with setae along both margins and further 5 to 

 6 obvious strong spines distributed along the outer margin. — The telson (fig. 4 i) reaches very little 

 beyond the inner ramus of the urojjods; its lateral margins are almost parallel for barely two-thirds 

 of the length and then the breadth narrows abruptly, each margin being divided into 4 sections of 

 about equal length by 3 small notches each of which has a thick and very long spine; the end which 

 is thus short is flatly rounded and provided with a pair of thick long spines separated by a shorter 

 spine. In front of the second of the very long lateral spines there is a short spine, between the 

 second and third long spines 4 — 6 smaller spines increasing graduallj' in length backwards, between 

 the third long lateral spine and the long terminal spine 6 shorter spines increasing graduall)' in 

 length backwards (fig. 4 k)'. — The jDleopods in the female are as usual unbranched, but they increase 

 greatly in length from before backwards, so that the fourth pair is a little longer than the fifth seg- 

 ment, the fifth pair however but little longer than the sixth segment, which is not much shorter than 

 the two previous segments taken together. In the male all the pleopoda are of about equal length 

 (figs. 4 d — 4 h), but a little shorter than usual in forms of this suborder and they differ considerably in 

 several points from the usual type. The peduncle increases a little in length from before backwards; 

 the outer ramus is almost similar in all pairs, consisting of a long joint divided obliqiiely at a little 

 distance from its base and ca. 8 (on the fifth pair) short joints; this portion has two longitudinal rows 

 of fairly short but strong, non-plumose setae. The inner ramus consists on the first pair (fig. 4 d) of 

 only a single oblong joint. On the second to the fourth pairs the inner ramus is well-developed and 

 increases a little in length backwards, being on the second pair (fig. 4 e) a little shorter, on the fourth 

 pair (fig. 4 g) a little longer, than the outer ramus; in all three pairs the inner ramus consists of a 

 long, unjointed basal portion and a distal portion divided into 7 or 8 short joints with similar setae 

 as on the outer ramus, but the proximal unjointed portion increases in length from before backwards 

 and on the second pair is a little shorter, on the fourth pair somewhat longer, than the jointed distal 

 portion. On the fifth pair (fig. 4h) the unjointed portion is, however, a little longer than the whole 

 outer ramus and a jointed portion is lacking. Further, the setigerous equipment on the unjointed 

 portion of the inner ramus offers some interest, as almost all the setae are tolerably transparent and 



■ This description of the telson has been based on the males as the telson in all my adult females was greatly 

 mutilated. There is however scarcelj- any sexual difference in this organ. 



The Ingolf-Expedition III. 2. 13 



