399 



The head and pereon are broader than in other species of the genus; 

 the width of the head is 1.6 times and its height two times more than 

 its length; viewed laterally, the anterior margin is straight below the 

 place of attachment of antennae I. The antennal gland is round, well 

 discernible (lateral view), and separated from the epistome. Tlie lobes 

 of the maxillipeds bear thin setae on the anterior surface and one long 

 submarginal spine each on the outer margin. 



The 2nd segment of pereopods I is slightly longer than twice its 

 width; the 5th segment has a small distal process bearing three spinules 

 and one spinule on its posterior margin; the 6th segment has one long 

 spine on the anterior margin. The distal process of the 5th segment of 

 pereopods IT is 1/4 the length of the 6th segment and bears six spinules. 

 Pereopods III- VII are strong. Pereopods V-VII bear one strong spine 

 on the anterior distal angle of both the 4th and 5th segments in females 



325 but only on the 5th segment in males. The telson is equal in length to its 

 width at the base; the length in females is 4/5, in males 1/2 the length 

 of the basipodite of uropods III. 



Distribution: Northern tropical (28° N., 155° W.), western 

 (Kuroshio) and eastern (coastal regions of California, Nasca ridge) 

 regions of the Pacific Ocean. It is an epipelagic species. 



12. Genus Themistella Bovallius, 1887 



Bovallius, 1887a: 22; 1889: 312; Bowman, 1973: 63. 



Minute (4 mm) crustaceans with a fairly broad pereon. The head is 

 large, its height somewhat exceeds its length, and is flat from the anterior 

 side. The eyes occupy almost the entire surface of the head. Somites I- V 

 of the pereon are fused in both sexes. Antennae I in females have two 

 segments, antennae II one segment, and both are rudimentary. The cone 

 of the antennal gland is small. The mandibles have a denticulate cutting 

 edge, the mandibular palp is absent in females. The outer lobe of max- 

 illae I bears four apical spines. The outer lobes of the maxillipeds are 

 narrow and drawed distally; the inner lobes are totally absent. The coxal 

 plates are fused with the somites of the pereon. Pereopods I and II have 

 a weakly developed chela formed by the distal process of the 5th and 

 6th segments. The 2nd segment of pereopods V-VII is distally broad- 

 ened. The pereopods V-VII distinctly longer than III-IV. Pereopods V 

 are longer than VI and VII. 



Type species: Themistella steenstrupi Bovallius, 1887. 



In general appearance, structure of the head, ratio of length of pere- 



326 opods III- VII, and structure of pereopods II, the genus Themistella is sim- 

 ilar to the genus Parathemisto, but in presence of a chela in pereopods I 

 and the structure of pereopods III-IV it is much closer to Hyperiella. 



This is a monotypic genus. 



