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



Hyperia Latreillei. 



T h e ra al e. 



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



The bodi/ is bi'oad and thick, but the pera^on is not at all tumid as in the female. 

 The pleon and nrus together ai-e a little longer than the perajon. The surface of all the 

 segments is even and lusti-ous 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 perajonal segments together; it is as 

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

 the tirst two and half the third perasonal segments. The antennal groove cominences below 

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



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

 the head hj a narrow strip. 



The fi7'st pair of antennas (PI. IX, tig. 31 — 34) in the adult male are longer than 

 the head and perason 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 followng joints together; these two last are equal in length. The tirst 

 joint of the fiagellum is more than tAvice as long as the whole peduncle, conical, and 

 about three tiines 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 Avith four stout hairs (Pl. IX, fig. 32). The flagellar joints are twenty-eight or 

 thirty in number. 



In the young male (Pl. IX, fig. 33 and 34) the antennas are of course much shorter 

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

 long as the whole peduncle, and sparingly 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 groAVS older the number of fla- 

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

 joint, Avhich sloAvly increases in length itself. In ~ verv young males just hatched the 

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

 at a closer examination the tip of the single flagellar joint Avill 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 antennas {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, Avhich is very Ioav. The second joint is only a little shorter 



