146 PROCEEDINGS OF THE NATIONAL MUSEUM vol.108 



ing to near end of exopod, inner margin with four short, thick setae 

 disposed along its length, the distal the largest and armed marginally 

 with a hyaline flange. Left endopod much shorter than right, but 

 nearly as long as the shortened left exopod, its outer distal margin 

 with two short lobed processes. 



Distribution: Suez Canal. Original record from two specimens, 

 taken in separate plankton collections at night, from Kabret and 

 Ismailia. 



Remarks: Since only the female of Ridgewayia typica and the 

 male of R. canalis are known, the question of their possible conspeci- 

 ficity has been considered in this study. It has been concluded from 

 the following differences in the first leg and the cephalic appendages, 

 exclusive of the antennule, that R. canalis is a distinct species and 

 does not represent the male of R. typica: 



Antenna: Endopod 8-segmented in typica, 7-segmented in canalis; last seg- 

 ment with 3 apical setae in typica, with 4 in canalis. 



Maxilla: Seven lobes in typica, of which three belong to the basal division; 

 five lobes in canalis, of which one belongs to the basal division. 



Leg 1: Exopod segment 1 without distal process on outer margin in typica, 

 with process in canalis. Apical inner spine of exopod segment 3 longer than last 

 two segments in typica, shorter in canalis. 



These characters have been taken from illustrations given in the 

 descriptions of the two species. The characters are easily determined 

 for the antenna and maxilla, and it is probable, unless immature 

 specimens were originally studied, that examination of the species 

 when again collected wUl show them to be as given. With the 

 exception of the spine length, the characters of the first leg need most 

 careful study from an advantageous view. Mere comparison of the 

 figures may not necessarily give exact detail of the armature of the 

 exopods. All of these differences should also help in identifying the 

 female of canalis. 



Ridgewayia marki (Esterly), new combination 



Lampoidopus marki Esterly, 1911, p. 219, pi. 1, fig. 4; pi. 2, figs. 13, 14, 20, 21; 

 pi. 3, figs. 25, 26, 28-31, 34; pi. 4, figs. 35, 38, 42.— Pinney, 1933, p. 142. 



Diagnosis (after Esterly): Length of both sexes about LO mm. 

 Metasome 5-segmented, somite of leg 1 fused with cephalic segment. 

 Rostrum broad and rounded at apex. Urosome female 3-segmented; 

 male 4-segmented; caudal rami about 3.5 times as long as broad in 

 both sexes. (See also p. 162.) 



Antcnnules reaching to end of caudal rami; female and left male 

 25-segmented. Right antennule male geniculate, 23-segmented, 

 "terminal portion 4-jointed." Antenna, exopod 8-segmented. Max- 



