152 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



Maxiilule (fig. 17) with well-developed basipod but without defina- 

 ble lines separating segments from one another. The first inner lobe 

 (gnathobase) comparatively large, prominently produced, oval in out- 

 line, bearing eight stout spines and five subapically placed setae. Just 

 distal to this lobe two narrow laciniae, each bearing four apical setae. 

 The proximal outer portion an unexpanded plate bearing nine setae, 

 of which the distal six are greatly lengthened. Between this group 

 of setae and the basal attachment of the exopod, a protrusion (epipo- 

 dite?) bearing a single setae. Exopod and endopod borne on the dis- 

 tal narrowed portion of the basipod, which has its inner part produced 

 as a small lobe bearing four setae. The endopod 2-segmented; its 

 proximal segment comparatively enlarged, with eight lateral setae; 

 the apical segment reduced, with six setae. Exopod constricted be- 

 yond its middle so as to form two setiferous portions, the proximal 

 bearing five lateral setae; the distal somewhat expanded and bearing 

 three lateral and three apical setae. 



Maxilla (fig. 19) with six distinctly developed lobes of which two 

 belong to the basal division, which is incompletely demarcated from 

 the second. An accessory seta on a short stalk at the proximal base 

 of the first lobe. The fifth lobe (the proximal of the third division) 

 the largest. The number of setae on the lobes as follows (lobes num- 

 bered from proximal to distal) : 



Lobes: 12 3 4 5 6 



Apical setae: 4 2 2 3 4 3 

 Basal setae: 1 2 



The reduced terminal portion of the maxilla indistinctly separated and 

 segmented, with three setae. 



Maxilliped (fig. 18) with short, nonsetiferous basal segment (present 

 in all dissections). Second segment with four lobes, the number of 

 setae from proximal to distal lobe, 1, 2, 4, 3. The longest setae that 

 of the first lobe and the proximal of the second lobe; both of these 

 naked. Two of the setae of the distal lobe extremely reduced. Third 

 segment with three plumose setae, between it and the endopod an 

 incompletely separated segment, distinct neither from the endopod 

 nor from the basipod. Endopod of five distinct segments bearing 

 setae as follows : 



Figures 14-27. — Ridgewayia gracilis, new species. 14-21, Female: 14, outline of anten- 

 nule, showing segmentation; 15, antennule, segments 13-15; 16, antennule, segments 

 1-4; 17, maxiilule, greatly enlarged; 18, maxilliped; 19, maxilla; 20, antenna; 21, anten- 

 nule, apical segments 22-26. 22-27, Male: 22, right antennule, apical segments; 23, 

 right antennule, segments 9-15; 24, leg 5, detail apex of left exopod, anteromedial view; 

 25, same, posterior view; 26, leg 5, detail right exopod and endopod, anterior view; 27, 

 leg 5, posterior view. 



