COPEPOD GENUS RIDGEWAYIA — WILSON 171 



They are included in table 3 as percentage figures determined in 

 the same way as those for gracilis and shoemakeri. 



Leg 5, Male: An unportant part of the generic definition as 

 now constituted is found in the modification and asj'mmetrical 

 development of the endopods of the male fifth leg. This is expressed 

 in the elongation of that of the right side in contrast to the shorter, 

 broadened endopod of the left side and m the varied armature of the 

 different species. The armature seemingly is specific in nature, 

 although with increased knowledge it may be found, in part, to define 

 gi'oups of species or even genera. In the known species, segmenta- 

 tion is suppressed in the adult, but since the subadult male (Ridge- 

 wayia sp., Tortugas) shows partial segmentation of the right endopod, 

 it may be that some species may be found in which at least the right 

 endopod is distmctly segmented. 



The right exopod is 2-scgmented in all the five kno\vn adult males 

 (including Ridgewayia sp., Madras). The first segment is very 

 similar in all the species, but the second segment shows definable 

 differences. The three American species are noticeably most similar 

 to one another not only in the shape and length of the segment but 

 in the presence of two similarly placed outer spines. In canalis 

 and the Madras male there is only one well-developed spine, the 

 second or even a third spine being suppressed or broken off in the 

 available specimen. Gurney's (1927) figure shows two spinous 

 points along the extended outer margin of canalis, and the exceedingly 

 shortened segment of the Madras male has a projection of closely set 

 points very suggestive at least of the remnants of the cuticular 

 points defining the placement of a spine. With this exception, 

 this segment of the leg of the Madras male, though shortened, is 

 more similar to the American species than it is to that of canalis. 



The left exopod is separable into three distinct segments in the 

 American species. The third segment is highly modified and is set 

 into a centrally recessed area of the expanded, strongly built apex 

 of the second segment. There is a higher degree of segmental develop- 

 ment in shoemakeri than in gracilis. In marki, the apical processes 

 and membranes are much more elongate than in either of the Tortugas 

 species, but in other respects the whole left leg shows more similarity 

 between shoemakeri and marki than exists between shoemakeri and 

 the associated Tortugas species. 



Although shortened, the left exopod of the Madras male is easily 

 correlated with that of the American species. The figure given by 

 Krishnaswamy (1953) is reduced in size and allows for little detail; 

 however, its outline is entirely credible and its structure interpretable 

 in light of knowledge of the American species. The outer spines of the 



