COPEPOD GENUS RIDGEWAYIA — WILSON 141 



Antenna: Outer ramus a little longer than inner, 7-8-segmented, 

 only the apical segment elongate. Inner ramus 2-segmented, the 

 first segment longer than the second, bearing 1-2 lateral setae; the 

 second with terminal portion expanded into two setiferous lobes, the 

 outer produced beyond the inner. 



Mandible: Masticatory blade not conspicuously expanded, pro- 

 duced or grooved, with about 7-10 shallowly incised teeth not sepa- 

 rated by any large gaps. Palp with broad, unsegmented basipod 

 bearing 3-4 lateral setae. Exopod 4-segmented, the two distal seg- 

 ments more or less defined. Endopod 2-segmented, with numerous 

 apical setae. 



Maxillule (unknown for canalis): Basal portion well developed, 

 with indistinct segmentation or none; its greater proximal part con- 

 sisting of an expanded inner lobe (gnathobase) bearing short, spini- 

 form setae; outer portion an unexpanded setiferous plate with 9-10 

 mostly elongate setae. Distad to this outer plate a reduced lobe 

 (epipodite) bearing (in the new species) a single seta (no seta shown 

 in illustrations for typica, marki). Inner side beyond gnathobase with 

 two narrow laciniae, each bearing 4-5 setae. Beyond these laciniae, 

 the basis elongated and produced on inner proximal side into setif- 

 erous lobe. Endopod attached just outside this lobe, 2-segmented 

 (apical segment not shown as separated in marki) ; proximal segment 

 greatly enlarged with several (6-8) lateral setae; apical segment re- 

 duced, with 5-6 setae. Exopod rather well developed, arising from 

 the basis nearly opposite the inner laciniae (clearly separated in the 

 new species, but not shown as demarcated in marki, typica), with 

 lateral and apical groups of setae (exopod entirely unsegmented in 

 typica and in the new species, but apex shown as demarcated in marki) . 



Maxilla: The whole equal to or a little longer than the basal 

 segment of the maxilliped, with three broad primary divisions ex- 

 panded into small setiferous lobes, and a reduced terminal portion 

 which may or may not be distinctly separated or segmented. Lobes 

 5-7 in number, of which 1-3 are on the proximal division ; the other 

 two divisions each with two lobes. Setae of lobes long and slender, 

 none conspicuously more developed than the others. 



Maxilliped: Not conspicuously enlarged, but its length 3-4 times 

 greater than that of the maxilla and longer than the first leg. The 

 basipod of 2-3 segments (a proximal, nonsetiferous segment not shown 

 in figures of other species, but present in the new species); second 

 segment with four lobes or groups of setae. Endopod shorter than 

 total basipod, of five well-defined segments; intercalated between it 

 and basipod an incompletely separated segment bearing two setae. 



Legs 1-4 slender, with nan-ow connecting pieces; bu-amous, both 

 rami 3-segmented. Inner seta on basipod segment 2 of leg 1. (Infor- 



