36 DE. W. T. CALMAN ON NEW OE EAEE 



Genus Paraleucon, gen. nov. 



Differing from Leucon in having only one pair of pleopods in the male sex. 



Type species P. siiteri, sp. n. 



The species described below resembles Heteroleucon aharoensis in the arrangement 

 of the teeth on the dorsal crest of the carapace. The segmentation of the endopod 

 of the uropods is much less distinct than in most other Leuconidae, and may be 

 regarded as forming a transition to the unsegmented condition found in Heteroleucon. 

 The number of thoracic exopods, howeverj and the presence of a pair of pleopods 

 in the male seem to require that this species should be distinguished generically 

 from the last. 



Paraleucon suteri, sp. n. (Plate IX. figs. 1-20.) 



LesGri])tion of adult Female. — Total length 2-9 mm. 



Carapace more than one-fifth of total length, compressed ; its vertical height a little 

 more than two-thirds of its length. The dorsal edge is nearly straight as seen from 

 the side, keeled, with a large tooth near the hind margin overhanging a rounded 

 excavation, in front of which the dorsal keel bears a varying number of irregular 

 serrations. The pseudorostrum is straight, directed obliquely upwards, and sharply 

 pointed. The length of the upper edge is less than one-fourth of the total length of 

 the carapace. The antenna! notch is well-marked and angular, defined below by a 

 triangular tooth, below which the anterior part of the lower margin is obscurely 

 serrated. On the side of the carapace are three subparallel ridges curving obliquely 

 downwards and forwards. 



The abdomen is longer than the cephalothoracic region. 



The antennules have the first segment of the peduncle little stouter than the second 

 and shorter than the second and third together. The outer flagellum is composed of 

 three segments and is shorter than the third segment of the peduncle. The inner 

 flagellum is unsegmented and about equal to the first segment of the outer. 



The antennae are composed of three segments. The proximal segment bears two 

 plumose setae. 



The mouth-parts are of the usual Leuconid type. The maxillae have two or three 

 small setce on the distal part of the inner edge. 



The branchial system is reduced, the lobules being represented only by two small 

 papillae. 



The first legs extend beyond the pseudorostrum by little more than the length of 

 their last segment. The basis is little shorter than the remaining segments together, 

 and the dactylus is nearly as long as the propodus. The exopod is shorter than the 

 basis. 



The second legs have tlie ischium distinct and the dactylus longer than the carpus. 



