170 CARL BOVALLIUS, AMPHIPODA HYPERI1DEA. I. 2. HYPERIID^E. 



Hyperia Latreillei. 



The male. 



PI. IX, fig. 31—43, and PI. X, fig. 1—13. 



The body is broad and thick, but the peraeon is not at all tumid as in the female. 

 The pleon and urus together are a little longer than the peraeon. The surface of all the 

 segments is even and lustrous as if polished; the segments of the peraeon are somewhat, 

 convex transversely, those of the pleon a little concave laterally. 



The head is almost as long as the first two peraeonal segments together; it is as 

 long as the head of the female but much narrower and less deep; the depth about equals 

 the first two and half the third peraeonal segments. The antennal groove commences below 

 the middle of the front side of the head, and is about as broad as high. 



The eyes occupy the whole surface of the head; they are separated at the top of 

 the head by a narrow strip. 



The first pair of antennw (PI. IX, fig. 31 — 34) in the adult male are longer than 

 the head and peraeon together, and distinctly shorter than the second pair. The first 

 peduncular joint is stout and thick, somewhat broader than long, and about twice as 

 long as the two following joints together; these two last are equal in length. The first 

 joint of the flagellum is more than twice as long as the whole peduncle, conical, and 

 about three times as broad at the base as at the apex; it is thickly covered with ol- 

 factory hairs; the second and third joints are somewhat shorter than the following ones, 

 but nevertheless longer than broad; the fourth joint is much shorter than the two preced- 

 ing joints together; the fifth and following joints are almost equal in length, cylindrical, 

 about fifteen times as long as broad, and sparingly set with short hairs; the last joint 

 is somewhat shorter, nine times as long as broad, with bulging sides; it is tipped at the 

 apex with four stout hairs (PI. IX, fig. 32). The flagellar joints are twenty-eight or 

 thirty in number. 



In the young male (PL IX, fig. 33 and 34) the antenna? are of course much shorter 

 and comparatively thicker, but of the same form. The first flagellar joint is scarcely twice as 

 long as the whole peduncle, and spai'ingly set with some few short hairs; the five or six 

 following joints are about as long as broad; the next ten to fifteen joints are nearly twice 

 as long as broad, all without hairs. When the animal grows older the number of fla- 

 gellar joints is increased by the formation of new ones at the apex of the first flagellar 

 joint, which slowly increases in length itself. In very young males just hatched the 

 first pair of antennae are very similar to that pair in the female, but comparatively longer; 

 at a closer examination the tip of the single flagellar joint will be found faintly divided 

 into two or three small articuli; the epidermis however does not at this early stage 

 indicate any articulation between these small articuli, or between them and the large basal 

 portion of the flagellum. 



The second pair of antennw (PL IX, fig. 35 and 36). The peduncle is scarcely as long 

 as the peduncle of the first pair. The first free joint is thick, as broad as long, and at its 

 side projects the glandular cone, which is very low. The second joint is only a little shorter 



