532 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



margins and only slightly attenuated below and distally, with an 

 oblong eye filling the anterior part of the head fully along the anterior 

 margin. Eurystheus atlanticus bears a strongly produced lateral head 

 lobe with a lageniform eye, the lower part of the eye filling the lateral 

 lobe and the neck reaching upward toward the top of the head. 

 Since that time, the two species have been recorded frequently and a 

 few more figures have been published but the interpretations have 

 strayed far from the original interspecific concepts of the genus. It 

 becomes practically impossible for the taxonomist to assign names 

 to populations in areas other than the type locality, South Africa. 



The two species, their varieties, and similar phenotypes have now 

 been reported from as far east as Micronesia, half a world away from 

 the type locality. 



Stebbing's concept of differences based on eyes was destroyed by 

 Tattersall (1922), who reported E. atlanticus with well-produced head 

 lobes that mixed together specimens having oval eyes entirely con- 

 fined to the lobes with specimens having lageniform eyes with a neck 

 stretched up onto the head proper. Apparently the lageniform eye 

 was associated with a terminal condition of adulthood. Chilton 

 (1921) reported specimens with the lageniform necks nearly obsolete, 

 but perhaps these should be considered as rudimentary necks just 

 developing rather than becoming obsolete. 



Walker (1909) decided that his E. gardineri and E. zeylanicus were 

 synonyms of E. atlanticus, bringing in species with variable eyes or 

 oval eyes confined to the head lobes. Thus, E. afer and E. atlanticus 

 differed basically by the amount of forward production of the head 

 lobe, E. afer with an oblong eye, E. atlanticus either with an oval eye 

 confined to the large head lobe or with a neck extending onto the 

 head. 



Then Pillai (1957) figured both species, distinctly showing a differ- 

 ence in sizes of head lobes, with oval eyes for E. atlanticus and slightly 

 oblong eyes for E. afer. Eyes of the latter species somewhat resembled 

 a modified version of a lageniform eye intermediate between the 

 original E. atlanticus and E. afer of Stebbing. 



J. L. Barnard (1961) figured a specimen assigned to E. afer having 

 head lobes similar to those of Stebbing's E. afer but with modified 

 lageniform eyes as shown by Pillai. 



Present materials provide an unusual population assignable to E. 

 atlanticus and carrying well-produced head lobes, oval eyes, and male 

 gnathopods within varietal extremes of E. atlanticus. Female gnatho- 

 pods, however, are identical to those of the male, a condition not 

 heretofore described. Apparently this is a distinct phenotype, but 

 whether it is sufficiently distinct to prevent interbreeding [is ^unknown 

 of course. Another group of specimens is composed only of females 



