COPEPODA FROM IFALUK ATOLL 13 



external. Spine at external margin of left 1st exopodal segment strong, 

 with broad, serrate, lamellar edge. 



P. rubrocinctus Bowman and Gonzalez 



6. Spine at external margin of left 1st exopodal segment strongly reduced. 



Segments 9-13 of clasping antennule greatly swollen and short, with 



spinuous process on 13th segment P. simplex Sewell 



External marginal spine of left 1st exopodal segment of leg 5 normally 

 developed, i.e., with lancet-shaped, finely serrated, marginal lamella, 

 large and strong. Segments 9-13 of clasping antennule moderately 

 swollen, of normal length, no spinuous process on the 13th segment . . 7 



7. Setae 2 and 3 of furca strongly developed, especially the basal parts greatly 



swollen, also with marginal spinules P. latisetosus Sewell 



Setae of furca normally developed, not thickened, barbed or plumose. . . 8 



8. Head and 1st thoracic somite, as well as 4 and 5, separate. 5th thoracic 



somite at apex narrowly rounded. . P. obtusatus Brady and Robertson 

 Head and 1st thoracic somite fused 9 



9. Thoracic somites 4 and 5 fused, lateral thoracic margin broadly rounded. 



Rostrum normally developed P. crassiremis Brady 



Thoracic somites 4 and 5 separate, lateral thoracic margin narrowly rounded. 

 Rostrum very big, strongly developed. Epimeral plates of 2nd thoracic 

 somite backwardly produced into pointed process. 



P. rostratus Bowman and Gonzdlez 



Genus Pseudocyclops Brady, 1871 

 Pseudocy clops crassiremis Brady, 1872 



Pseudocyclops crassiremis Brady, 1872, p. 7, pi. 2 (figs. 1-8); 1872a, p. 431, pi. 17 

 (figs. 1-8); 1878, p. 82, pi. 7 (figs. 1, 2), pi. 12 (fig. 14).— T. Scott, 1894a, 

 p. 237.— Giesbrecht and Schmeil, 1898, p. 126.— van Breemen, 1908, p. 144, 

 fig. 163.— Sars, 1919, p. 14, pis. 8, 9.— Rose, 1924, p. 481.— Pesta, 1927, p. 

 37.— Rose, 1933, p. 248, fig. 313.— Nicholls, 1944, pp. 10, 11.— Noodt, 

 1958a, p. 156. 

 Pseudocyclops crassicornis T. Scott, 1894, p. 233. 



Bottom dweller, usually found at depths of 20-30 fms. It was 

 actually recorded from Seaham Harbom- on the Durham coast of 

 England (1 male, 0.65 mm. length; Brady, 1872); off St. Monance 

 on the Firth of Forth of Scotland (rather scarce, no sex given: T. 

 Scott, 1894a); and from Korshavn on the Norwegian Skagerrak Coast 

 (some males and females, 9 0.86 mm., cT 0.80 mm. length; Sars, 1919). 

 The species thus appears to be narrowly confined to the North 

 Atlantic. 



Pseudocyclops obtusatus Brady and Robertson, 1873 



Psexidocyclops obtusatus Brady, 1872, p. 8 (nomen nudum). 



Pseudocyclops obtusatus Brady and Robertson, 1873, p. 128, pi. 8 (figs. 4-7). — 

 Brady, 1878, p. 84, pi. 12 (figs. 1-13).— T. Scott, 1894a, p. 233; Giesbrecht 

 and Schmeil, 1898, p. 126.— Brady, 1902, p. 55.— Sars, 1902, p. 131, pi. 88.— 

 T. Scott, 1902, p. 454; 1903, p. 112, pi. 6 (figs. 13-15).— Thompson and A. 

 Scott, 1903, p. 250.— Norman and T. Scott, 1906, p. 131.— Pearson, 1906, 

 p. 29.— van Breemen, 1908, p. 144, fig. 162.— Sars, 1919, p. 14.— Rose, 1924, 



