of the body. A. armatus is 1.80 to 2.02 mm. 

 total length (about . 50 specimens) and has 

 metasomal processes that extend beyond the 

 distal end of the genital segment. A. pacificus, 

 as described above, has a slender body of 2.20 

 to 2.43 mm. (seven specimens) and has meta- 

 somal processes that do not reach the distal end 

 of the genital segment. The male of A. pacificus 

 is not known. 



Euaetideus acntus (Farran, 1929) 

 (Plate 5, figs. 8-14) 



Occurrence 



Sta. 3. 3 adult females, 1.65 to 1.68 mm. 



Sta. 5. 5 adult females, 1.68 to 1.78 mm. 



Sta. 7. 1 adult female, 1.65 mm. 



Sta. 9. 1 adult female, 1.68 mm. 



Remarks 



The female of this species can easily be dis- 

 tinguished by the following characters : The 

 rostrum is very heavy and, in dorsal aspect, 

 distinctly set off from the remainder of the 

 head (fig. 8) ; the rami (fig. 10) are separated 

 by a deep, U-shaped incision, at the base of 

 which are two small knobs; the posterolateral 

 corners of the metasome are produced into 

 acute points that extend slightly beyond the 

 distal border of the second urosomal segment 

 (fig. 11) ; the dorsum of the prosome (figs. 8 

 and 9) has a pitted structure that is particu- 

 larly visible at the forehead and on the last 

 segment. 



The antennae and the mouth parts were fig- 

 ured and described in detail by Vervoort 

 (1957). The present specimens generally agree 

 with his description except for the maxilla. 

 The dagger-shaped spines on the fourth and 

 fifth lobes of the maxilla (fig. 12) are almost 

 identical in diameter, but different in length — 

 the one on the fourth lobe is the longer. Each 

 of the first to fourth lobes has a row of acute 

 spinules, instead of irregular rows of spinules. 



The first to fourth pairs of legs in general 

 agree with those figured by Vervoort (1957). 

 Some additional characters in the present 

 specimens are as follows : In stained specimens, 

 a line of demarcation is clearly visible between 

 the first and second endopodal segments of the 

 second leg. A row of fine spinules lies along the 



distal border of the second exopodal segment 

 in the second to fourth legs and on the distal 

 border of the second endopodal segment in the 

 third to fourth legs. The coxa of the fourth 

 leg has about 5 acute spinules at the insertion 

 of the internal seta (figs. 13 and 14). 



Euchirella truncata Esterly, 1911 

 (Plate 5, figs. 15-22) 



Euchirella truncata Esterly, 1911, p. 322; 

 plate 26, fig. 5 ; plate 28, fig. 35 ; plate 29, fig. 

 63; plate 30, fig. 71; plate 31, fig. 104. 



Euchirella propria Esterly, 1911, p. 321, 

 plate 27, figs. 14 and 20 ; plate 30, figs. 67 and 

 83; plate 31, fig. 85. 



Occurrence 



Sta. 3. 1 adult female, 5.40 mm. 



Sta. 5. 5 adult females, 5.56 to 6.06 mm. ; 



1 adult male, 4.60 mm. 

 Sta. 7. 5 adult females, 5.85 to 6.24 mm. ; 



7 adult males, 4.60 to 5.08 mm. 

 Sta. 9. 2 adult females, 5.71 to 6.14 mm. ; 



3 adult males, 4.89 to 4.99 mm. 

 Sta. 13. 1 adult female, 6.81 mm. 



Euchirella truncata was originally described 

 by Esterly (1911) from females obtained in the 

 San Diego, Calif., region of the eastern Pacific. 

 As suggested by Vervoort (1963), Euchirella 

 propria, erected on males alone by Esterly 

 (1911), seems to be synonymous with E. trun- 

 cata, for in the present study the two forms 

 were found in the same samples and were 

 closely similar in size as well as in anatomical 

 details. 



E. truncata has also been recorded from the 

 South Atlantic as E. gracilis (Wolfenden, 

 1911), from the North Atlantic as E. inter- 

 media (With, 1915), and from the Gulf of St. 

 Lawrence as E. acadiana (Willey, 1919) . 



Description of Female 



The female can easily be recognized by the 

 shape of the genital segment, which is more 

 swollen on the left side (fig. 15), and by the 

 presence of a single strong spine on the coxa 

 of the fourth leg (fig. 16). 



Description of Male 



The total length ranges from 4.60 to 5.08 

 mm. The prosome is about 4.2 times as long as 

 the urosome. The cephalosome and the first 



CALANOID COPEPODS FROM NORTH PACIFIC 



545 



