154 CARL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 2. HYPERIIDJE. 



Byperia medusarum. 



The ei/es occupy almost the whole surface of the head; they are divided into a right 

 and left portion, which are separated from one another by a very narrow strip at the 

 top of the head. 



The first pair of antennce (Pl. IX, fig. 2) in the adult male are scarcely half as 

 long as the whole length of the animal, somewhat shorter than the head and perseon 

 together, and about as long as the second pair. The first joint of the peduncle is stout, 

 somewhat longer than broad, and almost three times as long as the two following 

 joints together; the second joint is a little longer and broader than the third. The 

 first joint of the flagellum is much longer than the whole peduncle, nearly conical, with 

 the sides somewhat bulging; the inner and under sides are thickly covered with long ol- 

 factory hairs; the second and third joints are very short, broader than long; the 

 fourth joint is as long as the two preceding together; the fifth and following joints are 

 longer, equal in length, cylindrical, about six times as long as broad. In all the fla- 

 gellum has from twenty-seven to thirty joints. 



The second 2jair of antennce (Pl. IX, fig. 3). The peduncle is considerably longer 

 than the peduncle of the first pair. The first visible joint is thick, with bulging sides, 

 longer than broad, and at its side projects the glandular cone, which is only a little 

 shorter than the joint itself; the next joint is not half as long as the first; the last 

 peduncular joint is a little shorter than the two preceding ones together, and slightly 

 tapering. The first flagellar joint is much shorter than the last peduncular joint, thick 

 at the base and evenly tapering towards the apex; the second joint is a little shorter 

 than the first, cylindrical; the following joints are equal in length to the second, cjdindrical, 

 about six times as long as broad, and each provided with some few very short hairs. 

 The joints of the flagellum are about twenty-eight in number. 



The labrum (Pl. IX, fig. 4) is almost as long as broad, and bilobed, the incision 

 between the lobes being very deep; it is thickly covered with short, curved hairs. 



The mandibles (Pl. IX, fig. 5) have a thick, cylindrical stem, the incisive lamina 

 is almost triangulär, armed with seven to nine sharp, unequal teeth, and densely set with 

 short hairs; the molar tubercle is very large; the grinding surface is ovate consisting of 

 j'ows of small extant tubercles, each tubercle being tipped with a short hair bent at the apex. 

 Between the incisive lamina and the molar tubercle there is a tuft of long, strong bristles. 

 The secondary incisive projection of the lefl mandible is narrowly triangulär, and sharp- 

 pointed. The palp articulates with the mandible in a deep notch or groove at the lower 

 outer corner of the stem. The first joint of the palp is short, thick, and irregularly egg- 

 shaped; the second joint is nearly cylindrical, not fuUy twice as long as the first; the 

 third joint is longer than the second, narrow, elongate-lanceolate; the tip is set with 

 minute hairs. (Pl. IX, fig. 6). 



The lahimn is broad; the median projection is broadly rounded; the lateral pro- 

 jectious are semicircular and covered with short hairs. 



The first jiair of maxillce (Pl. IX, fig. 7) consist of a thick basal joint and two 

 lamintB; the principal lamina is tolerably long; the basal portion is almost cylindrical; 

 the apical portion forms a spoon-shaped, strongl)^ curved process; the margins and the 

 sides of this process are thickly covered with bristles; and at the middle of the under 



