234 CARL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 2. HYPERIID^, 



Hyperia thoracica. 



The male. 



PI. XI, fig. 38, 39, and 41. 



The body is broader and more tumid than that of the male of Hyperia latissima. 

 The head and peraeon together are fully as long as the pleon and urus together. 



The head is more than half as long as the coalesced portion of the pergeon. The 

 antennal groove is large, and commences above the middle of the front side. 



The first pair of antenna? in the adult male reach to the hind margin of the second 

 pleonal segment. The first joint of the peduncle is twice as long as the two following 

 together. The first joint of the flagellum is a little longer than the whole peduncle; the 

 second, third, and fourth joints are small; the next six increase in length, the following 

 are equal, slender, cylindrical, and about six times as long as broad. The flagellar joints 

 are twenty in number. 



The second pair of antenna? are somewhat longer than the first, and reach fully to 

 the hind margin of the first ural segment. The first free joint of the peduncle is as 

 long as the second, the third is not fully as long as the two preceding together. The 

 flagellar joints are eighteen in number. 



The peraion has the coalesced portion about twice as long as the two following 

 segments together, and quite as long as the first two pleonal segments together. The 

 sutures between the coalesced segments are visible only at the lowest parts of the sides; 

 higher up there are no traces of sutures, but the integument is entirely even, hyaline, and 

 homogeneous. In the dorsal line the hind parts of the last two segments are produced 

 into sharp-pointed, narrowly triangular processes, which are directed backwards. 



The first pair of perceopoda (PI. XI, fig. 38). The femur is tolerably broad, and 

 somewhat longer than the four following joints together; the front margin is strongly 

 convex; the hind margin is concave above and convex below. The genu is much 

 broader than long. The tibia is much produced at the lower hind corner, and armed 

 with two bristles. The carpus has the front margin convex; the hind margin is straight, 

 and provided with one notch, which carries a bristle; the front side of the carpal process 

 is about as long as a third of the hind margin of the metacarpus, and is armed with a 

 terminal bristle and another one on each margin. The metacarpus is fully as long as the 

 stem of the carpus; the front margin is convex, and armed with a bristle; the hind margin 

 is feebly concave, and finely serrated on its lower half. The dactylus is as long as 

 two-thirds of the metacarpus. 



The second pair (PI. XI, fig. 39) are not longer, nor more slender, than the first; 

 the reach beyond the middle of the carpus of the third pair. The femur is longer than 

 the four following joints; the front margin is feebly convex; the hind margin is straight. 

 The carpus is less dilated than in the first pair; the carpal process is shorter than the 

 stem of the joint; its front side is a little more than half as long as the hind margin of 

 the metacarpus; the margins are provided with five bristles. The metacarpus is much 

 longer than the stem of the carpus; the front margin is feebly convex, and armed with 



