192 CARL BOVALLTUS, AMPHirODA HYPERIIDEA. I. 2. HYPERIIDiR. 



Hyperia spinigera. 



Hyperia spinigera is one of the largest species of the genus and seems to be 

 a true Arctic form, only occasionally migrating into the temperate region. It comes near 

 to H. medusarum and H. Lotreillei, but is easily distinguished from both by the arma- 

 ture of the hind margin of the metacarpus of the first and second pairs of peraeopoda. 

 In the form of the rami of the uropoda it somewhat resembles H. galba, but it differs 

 by the broader rami and the shorter and stouter peduncles. 



The male. 



PI. X, fig. 33—39. 



The body is broad and stout with a very thick and hard integument. The pleon 

 arid urus together are considerably longer than the head and pera^on together. The 

 pleon is quite as long as the pera^on. 



The head is fully as long as the first two pergonal segments together; it is scarcely 

 broader than long, but deeper. The antennal groove on the front side commences a little 

 above the middle, and is higher than broad. 



The first pair of antennae, in the adult male are fully as long as the head, the pe- 

 ra>on, and the pleon together. The first joint of the peduncle is more than twice as long- 

 as the two following together. The first flagellar joint is almost twice as long as the 

 whole peduncle, tumid, and with bulging sides; the second, third, and fourth flagellar 

 joints are short; the fifth, sixth and seventh are increasing in length; the following are 

 subequal in length, slender, cylindrical, and about six times as long as broad. In all the 

 flagellum has about forty joints. 



The second pair of antennas are somewhat shorter than the first. The first free 

 joint of the peduncle is unusually thick and long, almost as long as the two following 

 joints together; the glandular cone is long and well developed. The first joint of the 

 flagellum is shorter than the last peduncular. The joints of the flagellum are about 

 thirty-five in number. 



The mouth-organs are like those in Hyperia Latreillei. 



The perceon. The first and second segments are equal in length; the following 

 four are a little longer and equal; the seventh is the longest but only a little longer 

 than the sixth. 



The ejrimerals are longer than deep; those of the first two pairs are as long as 

 the under margins of the corresponding segments, but the rest are a little shorter. 



The branchial sacks are broadly ovate, and somewhat shorter than the femora of 

 the corresponding pairs. 



The first pair of peraiopoda (PI. X, fig. 34 and 35) are almost stouter than the 

 second pair. The femur is very large, broadly ovate, with the front margin strongly 

 convex; it is fully as long as all the following joints together, and scarcely a third part 

 longer than broad. The genu is broader than long, with some long bristles at the lower 

 hind corner. The tibia is longer than the genu; the lower hind corner is not much 



