286 CARL BOVALLIUS, AMPHIPODA HYPEEIIDEA. 1. 2. HYPERIID^. 



Euthemisto libetlula. 



T h e m a 1 e. 



Pl. XIII, fig. 6—21, and 23—31. 



The bodi/ is less compressed than in the following species, but the persion is scarcely 

 broader than the first pleonal segment. A distinct median cai'ina runs dorsally from the 

 front riiai'gin of the first perreonal segment to the hind margin of the first ural segment, 

 but does never project into angular processes. The integument is thin and homogenous, 

 of an almost vitreous appearance. The head and pergeon together are scarcely as long 

 as the pleon and urus together. 



The head is comparatively smaller than in Euthemisto coinpressa; it is tolei'ably 

 compressed, but somewhat broader than the first peneonal segment. The upper side is 

 evenly rounded. The antennal groove commences just above the middle of the front 

 side. The under side of the head is feebly rounded. 



The eyes occupy the whole surface of the head. 



The first pair of antennce reach to the hind margin of the first pleonal segment. 

 The first joint of the peduncle is thick, cylindrical, and more than three times as long 

 as the two foUowing joints together; the second joint is fully twice as long as the third. 

 The first joint of the flagellum is elongated, tumid, and tapers evenly from the middle 

 towards the apex; it is not fully twice as long as the whole peduncle, and has the inner 

 side fi'inged with long olfactory hairs; the second flagellar joint is nearly as long as broad, 

 the third a little longer, the fourth is more than twice as long as broad; the following 

 are much longer, subequal, about seven or eight times as long as broad, and each is 

 provided with three bundles of short, geniculate hairs, three or four in each bundle. 

 The flagellar joints are twenty-eight or thirty in number. 



The second pair of antennce are longer than the first, and reach beyond the hind 

 margin of the last pleonal segment. The first free joint of the peduncle is as long as 

 broad; the second is half as long again as the first, and is fringed with hairs along the 

 under margin; the third is quite as long as the two preceding joints together, and has 

 the under margin fringed with hairs. The first joint of the flagellum is shorter than the 

 last peduncular joint, bulbous at the base, whence it gently tapers towards the apex; 

 the second joint is half as long as the first; the third is as long as the second; the follow- 

 ing joints are longer, subequal in length, and four or five times as long as broad; the 

 terminal joints are somewhat more slender than those near the base; each joint carries on 

 the under margin some short hairs. The flagellar joints are forty-five or forty-seven 

 in number. 



The labrum (Pl. XIII, fig. 6) is thick and deeply, but symmetrically, bilobed; the 

 lobes are smooth. 



The mandihles (Pl. XIII, fig. 7 — 12) are comparatively longer than those in Para- 

 themisto. The incisive lamiua is bent inwards, with the margin curved; the two upper- 

 most teeth are very large, the following are much smaller, broad, rounded, but sharp- 

 edged; at the base of the lamina there are tufts of long, hair-like bristles. The accessory 



