KONGL. SV. VET. AKADBMIENS HANDLINGAR. BAND. 22. N:0 7. 



157 



the outer margin is smooth; the inner margin is serrated along the lower half of its length, 

 with spine-like teeth; the inner ramus is elongate-lanceolate, serrated on the lower parts 

 of both margins with spine-like teeth. The second pair reach to the apex of the peduncle 

 of the last pair; the peduncle is linear, twice as long as broad, scarcely longer than the 

 inner ramus; the outer ramus is elongate, sharp-pointed; the outer margin is smooth, the 

 inner serrated as in the first pair; the inner ramus is elongate-lanceolate, serrated as 

 in the preceding pair. The third pair have the peduncle very broad, abruptly constricted 

 at the base, scarcely more than a third longer than broad at the apex; the outer ramus 

 is lanceolate, longer than the breadth of the peduncle, but not equal to its length; the 

 inner ramus is nearly as long as the outer; both rami are serrated as in the first pair. 

 The telson is as broad as long, obtusely triangular, equalling in length the last 

 ural segment; it is a little broader than the peduncle of the last pair of uropoda, and 

 more than half as long as the same peduncle. 



The female. 



PL IX, fie. 17—19. 



Hyperia medusarum, 0. F. Muller. ') 

 Fig. 1. The animal from the side. 2. The first pair of antennae. 3. The dactylus of the first pair of peneopoda. 



The body, especially the perason, is only a little wider than in the male; the pleon 

 and urus together are much shorter than the person. 



The head is a little broader than deep. 



The first pair of antennas (Fig. 2 above) reach scarcely below the under margin of 

 the head; the peduncle is thick and stout; the first joint is cylindrical, as long as broad, 

 and twice as long as the two following joints together; the second joint is only a little 

 longer than the third. The flagellum is one-jointed, much longer than the whole ped- 

 uncle, but not fully twice as long; it is broad at the base, tapering towards the apex, 

 not tumid, Avith almost flat sides; the margins are set with short, fine hairs, especially 

 at the apex; on the inner side there are some few long olfactory hairs; no trace of ter- 



J ) The original of this figure is the typical specimen for Hyperia spinipes, A. Boeck, most kindly sent 

 to me by the late author in exchange for male specimens of the same species, which I had captured in 1869 

 of the »Koster» Islands, the west coast of Sweden. 



