A New Genus of Phreatoicidae. 219 



Gen. Hypsimetopus, gen. nov. 



Generic Characters. — Very like Phreatoiciis as to the general 

 form of the body and the structure of the mouth-parts and 

 several appendages. The cephalon, however, is relatively larger, 

 being higher in front, and also deeper than the succeeding 

 segment, to which it is freely articulated ; the infero-lateral 

 comers are produced forwards as an angular projection along 

 the sides of the first joint of the lower antennae ; the inferior 

 margins, at about two-thirds of the length of the head from the 

 front, curve upwards and slightly forwards to mark off on each 

 side a large area (cheek), which, however, does not project 

 outwards. The epistome forms a conspicuous transverse ridge 

 below the base of the lower antennae. 



First segment of pereion about as long as the succeeding seg- 

 ment, with its antero-lateral corners produced forwards. Pleon 

 relatively rather shorter than in Phreatoiciis, but not so short as 

 in Phreatoicoides, the side-plates only slightly produced, and the 

 vertically suspended pleopods almost entirely exposed. 



First appendage of pereion in the male with enormous sub- 

 ohelate hand. 



Remarks. — This new genus may easily be distinguished from 

 Phreatoiciis and Phreatoicopsis by the shape of the head, and also 

 by the longer first segment of the trunk, with which it is very 

 movably connected ; this is not the case in the other two genera. 

 In these characters, except in the relative length of the first 

 segment of the trunk, it is in close agreement with Phreatoicoides, 

 but, besides other differences, it fundamentally differs from that 

 genus by the possession of an epipodite on each of the last three 

 pairs of pleopoda, agreeing in this respect with the two first- 

 mentioned genera. The name is suggested by the relatively high 

 forehead in comparison with Phreatoiciis. 



Hypsimetopus intrusor, sp. nov. 



Specific Characters. — Form of body i-ather slender, surface 

 smooth. Eyes not formed. First four segments of pereion of 

 subequal length. Pleon only a little deeper than the pereion, its 

 length measuring 45 as compared with the cephalon and pereion 

 combined as 100 ; terminal segment with which the telson is 



