170 



PROCEEDINGS OF THE NATIONAL MUSEUM 



difference in the total number of setae on the third endopod segment 

 of legs 3 and 4, as shown in table 2. 



Leg 5, Female: This appendage is so similar in the four species in 

 which the female is known that only very precise examination reveals 

 the small differences that do exist. The leg of typica differs notice- 

 ably'^ from the American species only in the shortness of the inner- 

 most apical spine of the third exopod segment (see key, p. 173). 

 Differences in the three American species are found only in the com- 

 parative lengths of the basal joints of the setae of the exopod and 

 endopod and in the placement of the proximal inner and outer setae 

 of the second endopod segment. These latter differences have been 

 expressed in the text of the descriptions of the new species as the 

 percentage of the inner margin of the segment. The length of the 

 outer apical spinous process and of the basal portion of the outer 

 apical seta of the endopod are expressed as a similar percentage. 

 There is a striking difference between some of these points in the two 

 Tortugas species (figs. 5, 28 and table 3). From the figure given for 

 marki, the placement of the setae is very similar to shoemakeri. 

 Esterly's (1911) figure of marki does not show the outer spinous proc- 

 ess. R. typica seemingly differs from the others in the much closer 

 placement of the proximal inner seta to the base of the segment. 



Table 3.— Female leg 5, Ridgewayia. Ratio of certain characters of endopod 

 segment 2, expressed as percentage of total length of inner margin of segment 



(KEY; A, distance between base of inner margin and placement of first inner seta; B, distance between 

 base of inner margin and placement of first cuter seta; c, length of outer spinous process; d, length of basal 

 joint of outer apical seta) 



Since these characters of the endopod may be useful in differenti- 

 ating species, a comparison has been made in table 3 between the 

 two new species and the other species. Measurements were made 

 with a millimeter rule on the illustrations given for tyjnca and marki. 

 These, of course, do not represent exact measurements, but in the 

 absence of specimens they serve ver}^ well for comparative purposes. 



