KONGL. SV. VET. AKADEMIENS ITANDLINGAR. BAND 21. N:0 5. 31 



The head is more than twice deeper than long, the anterior side deeply excavated; 

 the rostrum is broad, triangular, curved downwards, almost as long as the rest of the head. 

 The head with the rostrum is a little shorter than the first pereional segment. 



The eyes (PI. IV, fig. 3) are ovate, a little prominent, placed a little above 

 the base of the first; pair of antennas. They consist of about 40 ocelli each. The ovate 

 prominence formed by the eyes is vertical, almost twice as long as broad. Most of the 

 ocelli consist of two elements each, some of them are composed of three, and a few ones 

 of four crystalline elements. The ocelli are irregularly scattered over the whole surface 

 of the ocular prominence but more decidedly crowded at both the ends. 



The first pair of antenna? (PI. IV, fig. 4 and 5) are a little thicker in the female than 

 in the male, but of the same form. They are much shorter than the head and the first 

 pereional segment together. The peduncle consists of three joints; the first is much the 

 largest, as thick as long, the second is longer than the third, all are provided on the 

 upper side with a finely serrated crest. From the upper anterior corner of the third joint 

 issues a peculiar bristle or spine provided with slender hairs at the tip. Possibly this 

 appendix is an homologon of the accessory flagellum in the Gammarids and Synopids. 

 The first joint of the flagellum is very large, somewhat compressed, fringed with long hairs 

 along the inner side; it is about a third longer than the peduncle. The following joints 

 are small, four in number in the male, two or three in the female. They are provided 

 with slender hairs and olfactory glands. (PI. IV, fig. 5.) 



The second pair of antenna? (PI. IV, fig. 6 and 7) are much longer than the first, 

 narrow, compressed, four-jointed; the first three joints represent the peduncle, the fourth 

 the flagellum; this in young males has two or three small terminal joints, evanescing with 

 the growth of the animal. The first joint of the peduncle is short, the second longer, the 

 third Jonger than the two preceding together. The upper margins of all the joints are 

 fringed with minute hairs. The flagellar joint is a fourth longer than the last peduncular one, 

 formed as the blade of a dagger. It is fringed with minute hairs along the upper margin, 

 and tipped with the rudiment of a small terminal joint carrying two long hairs. In a young- 

 male two such terminal joints are distinctly visible, the last the longest. (PI. IV, fig. 7). 



The mouth-organs are well developed. The labrum is very broad, emarginate at 

 the hinder margin, convex at the anterior (PI. IV, fig. 8). 



The mandibles (PI. IV, fig. 9) are comparatively small, the masticatory process is short 

 and broad, with the surface striated by fine lamella}; on the inner side of this process 

 the basal portion is densely covered with short curved strong spines pointing downwards. 

 Between the process and the base of the palp there is a projecting crest fringed with long 

 slender hairs. The palp is fixed a little above the middle of the basal portion; the. first joint 

 is the shortest, the second the longest, sparingly fringed with short hairs along the 

 inferior margin, and provided with some bundles of long hairs at the upper outer corner. 

 The third joint is a little shorter than the second, tapering towards the apex and feebly 

 curved; it carries a row of very delicate hairs on the underside of the attenuated apex. 



The first pair of maxilla? (PL IV, fig. 10) consist of a stout basal portion, almost 

 cubical, and wo narrow, linear, feebly curved laminae; the outer is the longest; both are 



