Amphipüda Synopidea. 27 



corner tnuicated, as long as the first two pei'eional segments. The 

 epinieral of" the third segment is as long as the segment, but twice as 

 deep, ronnded at the anterior margin, straight at the hinder. That 

 of" the fourth segment is fully as long as the segment, the anterior 

 margin rounded, the inferior straight, the lower hinder corner truncate, 

 and the hinder margin deeply excavated. The epimeral of the fifth 

 segment is longer than the segment and longer than deep, with ob- 

 tuselv rounded corners. The epimerals of the sixth and seventh seg- 

 ments are smaller, not so deep as the preceding, scarcely longer than 

 the corresponding segments, with feebly rounded corners. 



The branchial sacks are very large, thin, showing very broad white 

 crests or bauds crossing each other at acute angles. They are fixed 

 at the bases of the second to seventh pairs of pereiopoda. 



The ovitectrices [PI. Ill, fig. 49] are shorter than the branchial 

 sacks, lanceolate, four on each side. 



The ßrst -pair of pereiopoda [PI. Ill, fig. 50] are enormously deve- 

 loped, and characterize the animal at once. The femur is long and 

 narrow, slightly bent at both ends; the genu is tolerabl}^ long and 

 stout; the tibia is shorter; the carpus a little longer, but transformed, 

 and turned round backwards, pressed against the metacarpus with the 

 whole length of the joint, thus turning round the metacarpus so that the 

 original anterior corner seems to be the posterior. The metacarjnis is 

 globularly inflated, bordered by sharp, recurved teeth along the under 

 margin, against which the dactylus impinges; the anterior corner is pro- 

 vided with five tooth-shaped tubercles and two movable, strong bristles- 

 The dactylus articulates against the apparently hinder corner of the me- 

 tacarpus, it is quite as long as the underside of the metacarpus, feebly 

 curved, without teeth or serrations. The hand thus forms a most po- 

 werful instrument for holding fast the animal to the body of its host, 

 the animal probably living as ecto-parasite on sharks, and other larger 

 fishes, principally from greater depths. 



The second pair [PI. Ill, fig. 61]. The femur is long, smooth, 

 broader at the lovver end; the genu is of an unusual length, a little 

 shorter than the femur and longer than the carpus; the tibia equals 

 half the length of the femur; the carpus is longer, richly beset with 

 hairs; the metacarpus is short, broadly triangular, surrounded with hairs. 

 The very ?,nvA\\ dactylus \s articulated at the middle of the lower margin of the 

 underside of the metacarpus, not as usual at the anterior corner. The 

 part of the margin, against which the dactylus impinges, is denticulated. 



