12 CAKL BOVALLIUS, AMPHIPODA HYPERI1DEA. 



longer (3 : 2). The third and fourth segments are the longest, the first and seventh the 

 shortest. 



The first pair of pereiopoda (PI. I, fig. 12) are long and slender. The epiineral is 

 longer than deep, almost quadrangular, the lower corners rounded; the epimerals of the 

 following pairs have all the same form. The femur is four times longer than broad, 

 linear, the margins smooth. The genu and tibia are short, the carpus elongated, almost 

 linear, fringed with long slender hairs along the posterior margin and at the lower 

 anterior corner. The metacarpus is elongate-ovate, considerably shorter than the carpus 

 (4:3), beset with long slender hairs all around, the lower anterior corner feebly produced 

 on both sides of the base of the dactylus; the posterior margin is sparingly serrated. 

 The dactylus (PI. I, fig. 13) is very long, longer than half the metacarpus (11 : 18), 

 straight, with a deep circular notch at the base. At the bottom of this notch is a small 

 hole, probably the opening for a metacarpal gland. The posterior margin of the dactylus is 

 bordered with very short fine hairs. Long string-formed glands are to be seen in all the joints. 



The second pair (PI. I, fig. 14), are longer than the first. The femur, of the same 

 form as in the first pair, carries a few long hairs at the lower posterior corner; the genu 

 and tibia are short, provided with some hairs. The carpus is scarcely longer than the 

 metacarpus, both less richly beset with hairs than in the first pair. The metacarpus without 

 projections. The dactylus feebly curved, as long as half the metacarpus, provided with 

 a small hole at the base. Glands as in the first pair. 



The third and fourth pairs (PI. I, fig. 5, and PL II, fig. 6 and 7) are equal in length 

 and of the same form. The genu is uncommonly long, smooth; the three following joints 

 are long, microscopically serrated along the posterior margins, and provided with equidistant, 

 very minute spines. The dactylus is feebly curved, longer than half the metacarpus. 

 Glands as in the first pair. 



The fifth pair (PI. II, fig. 8), as in all known species of the genus Tyro, are deve- 

 loped into a kind of jumping organ; at the same time they serve as a good weapon, the 

 femur being produced into a very strong spine. The femur is long, linear, slightly 

 serrated along the anterior margin and coarsely along the posterior; it is shorter than the 

 three following joints together. The lower anterior corner projects into a very strong, 

 straight, sharp process, twice longer than the genu. The tibia is much shorter than 

 the carpus, both are smooth, almost linear. The metacarpus is very slender; it equals 

 scarcely a third of the length of the carpus. The dactylus is small, feebly curved. 



The sixth pair are considerably shorter than the fifth. The femur is a little more 

 dilated, broader below. The tibia is longer than the carpus, the metacarpus as long as 

 the carpus; these three joints are slightly serrated along the anterior margins. The 

 dactylus is curved, with a hole for the metacarpal gland at the base, (PL I, fig. 15). 



The seventh pair (PL I, fig. 16 and 17) are shorter than half the fifth pair, and about 

 as long as the femur af the same pair. The tibia is longer than the carpus, the meta- 

 carpus is elongate-ovate, finely serrated along the anterior margin; it is longer than the 

 carpus. The dactylus is long, feebly curved. 



Branchial sacks are attached to the epimerals of the second to sixth pairs, those of 

 the fifth pair are the largest. 



