COPEPODA FROM IFALUK ATOLL 143 



Dactylopodia may disappear as a junior objective synonym of Dac- 

 tylopusia. 



Genus Diarthrodes Thomson, 1883 

 Diarthrodes nobilis (Baird, 1845) 



Figures 51, 52 



Arpacticus nobilis Baird, 1845, p. 155. 



Westiooodia nobilis. — V^tova, 1028, p. 359. — ^Marine Biological Association, 1931, 



p. 163. — Fraser, 193G, p. 26. — Marine Biological Association, 1957, p. 167. 

 Farawestuwodia nobilis.— SeweW, 1940, pp. 236, 352, 357, 366, 369, 370, 372, 375. 

 Diarthrodes nobilis Dahl, 1948, p. 95.— Lang, 1948, p. 529, fig. 216.— Klie, 1949, p. 



122.— Maghraby and Perkins, 1956, p. 491.— Roe, 1960, p. 279. 



Material. — Loc. 590, 1 ad. 9, 0.43 mm. length. 



Description.— The following is based on the above-mentioned 

 specimen, which has been dissected and the appendages mounted. 



Adult female, total length 0.43 mm.; greatest diameter 0.18 mm.; 

 length of longest furcal seta 0.29 mm. 



Body strongly built, with well-developed, ovoid cephalothorax and 

 short abdomen; proportional length of cephalothorax and abdomen 

 is 20:9. In dorsal view body moderately slender, with marked 

 division between cephalothoracic and abdominal parts (fig. 52a). 

 Head and 1st thoracic somite completely fused to form cephalic 

 somite, which is longer than combined lengths of thoracic somites 2-4, 

 in proportion of 15:9, measm^ed in lateral aspect. Line of back, in 

 lateral view, broadly curved, curving smoothly into well-developed 

 rostrum, which points almost straight down (fig. 51a). Kostrum 

 triangular with rounded apex, as long as first two antennular seg- 

 ments, in dorsal aspect clearly visible and separated from cephalic 

 somite by deep groove. Lateral margins of thoracic somite well 

 produced, especially anterolateral corners, covering greatest part of 

 oral appendages. Epimeral plates of thoracic somites 2 to 4 well 

 developed, rounded in lateral view, in 3rd somite slightly, and in 4th 

 somite strongly, backwardly produced. 



5th thoracic somite small, invisible from above but distinctly 

 visible in lateral aspect. Abdominal somites 1 and 2, forming genital 

 somite, are distinctly separate in this specimen; somites 1 and 4, 

 and 2 and 3, have same length, latter being largest. Anal somite 

 longest somite of abdomen, with very broadly rounded, hyaline anal 

 operculum, placed at distal end of somite. No spinules on dorsal 

 surfaces of abdominal somites, but spinules occur on ventrolateral 

 surfaces of somites 2, 3, 4, and on lateral aspect of anal somite near 

 insertion of furcal rami. 



Furcal rami much broader than wide (proportion 7:3); there 

 are 5 marginal setae and one appendicular seta on each ramus. Seta 



