COPEPOD GENUS KIDGEWAYIA — WILSON 161 



Description: Length, 0.665-0.69 mm. Somite of leg 1 separated 

 from cephalic segment. Urosome 4-segmented ; caudal rami with more 

 or less distinct division of the outer margin near the base (representing 

 incipient division of a reduced fifth segment ?) ; fom'th segment Avith 

 distal row of fine spinules ventrally and on the lateral areas of the 

 dorsal side; caudal rami covered with hairs on both sides. Caudal 

 setae of same relative lengths as in gracilis and shoemakeri, none 

 jointed basally, but the longest jointed near the end as shown for 

 gracilis in figure 1 . 



Antennules alike, reaching just beyond metasome; with 25 free 

 segments; segment 9 somewhat elongate and partially divided by a 

 line running from the inner margin to the middle of the segment, with 

 two setal gi'oups (fig. 37); segments 1 and 2 subequal in length; the 

 three apical segments elongate, the last two subequal to one another. 



All cephalic appendages weakly developed, but fully segmented. 

 Exopod of antenna 8-segmented. Maxilla with six lobes, of which 

 two are on tlie basal division. 



Legs 1-4 fidly segmented; segmentation and setation exactly as in 

 gracilis and shoemakeri; all setae jointed. Leg 1 resembles the adult 

 of gracilis and shoemakeri, but the processes of the outer margin of 

 the exopod segments are not fully developed. 



Leg 5 (fig. 36): First basipod segments well developed, connected 

 by medial plate. Both exopods 2-segmented, the distal segments 

 elongate and of similar length, the left broader than the right. Right 

 exopod 2 with an outer medially placed spine that reaches to end of 

 segment; distaUy with two shorter spines and a long apical spine equal 

 to about three-fourths the segment length; distal inner portion with 

 three closely set, jointed setae. Left exopod segment 2 w4th medially 

 placed spine on outer margin, spine reaching beyond apex of segment; 

 apex with three membranous spmes of gi*aduated length, increasing 

 from outer to inner; the innermost with a stout inner marginal scle- 

 rotization; at inner apex of segment, a conspicuous hyaline projection 

 overlying base of inner spine. Right endopod longer than left, its 

 proxbnal part partially segmented; the apex armed with setae and 

 processes; of these, the outermost a stout spiniform process arising 

 laterally; setae four in number, all jointed basally. Left endopod 

 broad, armed near distal part on anterior side with a slender surface 

 seta; otherwise closely resembling the unarmed endopods of the 

 adult shoemakeri and marki. 



Remarks: It does not seem possible to relate this subadult male to 

 either of the Tortugas species. In many calanoid families the develop- 

 ment of the fifth leg is progressive, and, if such were known to be true 

 in Ridgewayia, it might be assumed that these copcpodids represent a 

 third unlalo^vn species in which the right exopod may have inner 

 apical setae, and the right endopod is also armed with setae. How- 



