98 U.S. NATIONAL MUSEUM BULLETIN 258 



The type species of a new genus to be described below is closely 

 related to Halirages mixtus and Bouvierella carcinophila but possesses 

 a small, scale-like, semi-articulated accessory flagellum. 



No species of Halirages bears an accessory flagellum, except that 

 H. julvocinctus and H. mixtus have a broad distal process on article 

 3 of antenna 1. Other species of Halirages and Bouvierella lack this 

 process. It is similar to the structure found in some species of Ponto- 

 geneia (Eusiridae) . In that family, J. L. Barnard (1964c) removed 

 from Pontogeneia four species to be included in a new genus Accedo- 

 moera. All bear a distinct accessory flagellum. Retained in Ponto- 

 geneia were species lacking any accessory flagellum and those having 

 a distal process on article 3 of antenna 1. Although the character 

 distinction is minor, this course is followed in the present case. The 

 alternate solution would be the removal of H. mixtus to Bouvierella 

 and the inclusion of the species at hand in that genus. The present 

 species cannot be assigned to Halirages because of the short telson, 

 the short peduncle of uropod 3, and the presence of an accessory 

 flagellum. It differs from Atylopsis by the absence of inner lobes on 

 the lower lip. 



Oligochinus, new genus 



Oligochinus Light, 1941 (nomen nudum). 



Diagnosis. — Lower lip lacking inner lobes; gnathopods subchelate, 

 articles 5 and 6 not elongated; palp of maxilla 1 normal, not reduced 

 in size; pereopodal dactyls not pectinate; accessory flagellum dis- 

 tinct, very short, scale-like but articulate, not directly fused to 

 chitinous edge of article 3 of antenna 1 ; telson short, deeply emargi- 

 nate distally ; peduncle of uropod 3 short; body lacking dorsal processes. 

 Generic name masculine. 



Type species. — Oligochinus lighti, new species. 



Relationship. — Distinguished from Halirages Boeck by the short- 

 ened telson and peduncle of uropod 3 and the presence of a distinct 

 accessory flagellum; distinguished from Bouvierella Chevreux by the 

 presence of a distinct accessory flagellum. See previous discussion 

 for other details. 



The writer has been able to recognize this entity by examining 

 specimens labeled "Oligochinus" in the collections of the Department 

 of Zoology, University of California, Berkeley (in the year 1951). 



Oligochinus lighti, new species 



Figures 9-10 



Diagnosis. — With the characters of the genus. 



Descriptive notes. — Posterior edges of pleonal epimera minutely 

 serrate; posterior margins of coxae 1-4 with 1-3 long spines; males 

 and females similar. 



