KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 22. N:0 7. 309 



as long as broad, the last is a little shorter; all are sparingly provided with short hairs. 

 The flagellum consists of seventeen joints. 



The second pair of antennas (Pi. XIII, fig. 32, and p. 305, fig. 3) are scarcely longer 

 than the first pair; the third peduncular joint is somewhat shorter than the two preced- 

 ing together. The first joint of the flagellum is as long as the last peduncular joint, but 

 more slender, and tapers towards the apex; the following are shorter but increasing in 

 length; the last four joints decrease in length towards the apex. The flagellar joints are 

 eighteen in number. 



The mouth-organs are like those in Euthemisto libellula. 



The perceon. The first segment is considerably longer than the second, the last 

 three are subequal in length. Sometimes the four last segments show a sharp-pointed an- 

 gular projection in the median line, those of the two last segments being the largest, 

 but more often the three last, or only the two last segments are provided with such a 

 projection, and in very young animals often all the segments want projections, but as a 

 rule they are distinct even there, though very feebly developed. 



The epimerals are comparatively deeper than in Euthemisto Gaudichaudii, but not 

 as deep as in E. libellula. That of the fifth pair of perasopoda is more than twice as 

 broad as deep. 



The branchial sacks are comparatively larger than in Euthemisto libellula, and are 

 rounded below. 



The first pair of peroeopoda (PI. XIII, fig. 33) are a little shorter than the second. 

 The femur is narrow, linear, and nearly as long as the four following joints together. 

 The genu is broader than long, and is fringed with long, hair-like bristles on the under 

 margin. The tibia is a little longer than the genu, a little produced below, and fringed 

 with long bristles. The carpus is longer than the two preceding joints together; the 

 front margin is feebly convex and sparingly set with long bristles; the hind margin and 

 the inner side are thickly covered with long, slender bristles. The metacarpus is as 

 long as the carpus, tapering towards the apex, and has the front margin convex and 

 fringed with long bristles; the hind margin is straight, serrated, and provided with a 

 single bristle at the middle, as in Euthemisto Gaudichaudii. The dactylus is smooth, 

 and not fully half as long as the metacarpus. 



The second pair (PI. XIII, fig. 34) do not reach quite to the apex of the carpus in 

 the third pair. The femur is narrow, linear, and as long as the four following joints 

 together. The tibial process is a trifle shorter than half the stem of the carpus, and is 

 fringed with long bristles. The carpal process is shorter than the rest of the joint, and 

 is in the adult male three-fourths as long as the hind margin of the metacarpus, and 

 provided with a terminal spine (PI. XIII, fig. 34); in the young the carpal process is 

 much shorter, but always about half as long at the metacarpus. The metacarpus is 

 somewhat shorter than the stem of the carpus, and tapers towards the apex; the front 

 margin is fringed with long bristles; the hind margin is finely serrated. The dactylus 

 is feebly curved, and more than half as long as the metacarpus. 



The third and fourth pairs (PI. XIII, fig. 35 and 36, and p. 305, fig. 5). The 

 femur is scarcely more than twice as long as broad; the front margin is feebly convex 



