Al exceeding caudal rami by about 2 segments; ter- 

 minal segments (Fig. 161) of moderate length and 

 width. Armature as Table 4. 



A2 Re2-3 not fused, otherwise as shown by Park 

 (1970, fig. 3): 



Mn Bl with 3 inner setae. Mn blade (Fig. 183) 

 relatively large; large rounded ventral tooth, 1 broad 

 irregular midlength tooth followed by rounded 

 bicuspid, and dorsal projection with 2 sharp, narrow 

 teeth, 1 tricuspid, and dorsal seta. 



Mxl as shown by Park (1970, fig. 5); gnathobase 

 with 4 proximal posterior setae and short spinelike 

 distal anterior seta. B2 with 7 inner setae. Proximal 

 part of Ri with 7 proximal and 7 distal setae; Ri ter- 

 minal segment with 9 setae. 



Mxp as shown by Park (1970, fig. 7); Bl with 

 spinules midlength on inner edge; distal lobe with 

 short spinules, 3 setae, and short truncate process. B2 

 with short longitudinal row of spinules on proximal in- 

 ner edge. Ri4-5 outer setae lightly plumose, thin and 

 relatively short. 



PI (Fig. 184) Re2 outer distal spine reaching beyond 

 base of Re3 outer distal spine. PI Ri with moderate 

 lobe; setae asymmetrical as described above. 



P2 (Fig. 185) Rel outer distal spine smaller than 

 outer spines of Re2-3. 



P3 (Fig. 186) B2 outer distal edge with 2-3 small 

 teeth. 



P4 (Fig. 187) Bl inner margin with hairs, without 

 inner seta and without transverse row of setules. Re 

 outer spines smaller than on P2-P3. 



Re terminal seta with following number of teeth: P2 

 (55-63); P3 (ca. 55); P4 (ca. 48). 



distal edge, left wider than right. Right Rel-2 nearly 

 fused. Inner edge of left B2 and Re3 with long hairs. 

 Each Re with moderate bladelike terminal process, 

 longer on right. 



Remarks 



Park (1970) indicated M. crassus PI Ri with "3 or 4 

 setae"; his illustration (fig. 8) shows right PI with 3 

 setae, as does the illustration of male right PI by 

 Grice and Hulsemann (1967, fig. 24). Park's illustra- 

 tion (fig. 11) of male left PI shows 3 setae, in agree- 

 ment with specimens examined in the present study. 

 Pl of holotype had been removed prior to deposit. 



Mimocalanus crassus is the only Spinocalanidae 

 with asymmetrical PI. Mimocalanus crassus is also 

 the only Spinocalanidae with no outer seta on P3-P4 

 Ri3; no inner seta on P2-P4 Bl; Mxl B2 with 7 inner 

 setae, Ri proximal part with 7 and 7 setae, and Ri ter- 

 minal segment with 9 setae. Mimocalanus crassus is 

 the only Mimocalanus species with short, lightly 

 plumose outer setae on Mxp Ri4-5, and without inner 

 transverse row of setules on P4 Bl (see M. major). 



Distribution 



Arctic Ocean 



Canadian Basin: Present study, 400-2,500 m. 

 Indian Ocean 



West: Grice and Hulsemann (1967), 2,000- 

 3,000 m. 

 Atlantic Ocean 



Caribbean Sea: Park (1970), 487-2,800 m. 



Male.— Length 0.78-1.36 mm (Figs. 188, 189). 

 Prosome in dorsal view robust ovoid; anterior 

 irregular, head rounded. In lateral view with irregular, 

 abrupt forward slope. Prosome length 2% times 

 urosome. Caudal rami length equaling width. 



Al reaching middle of urosome segment 2. Al 

 segments 8-9 relatively elongate. VIII-2s, le; XI- 

 2s, le; remainder as Table 4. 



Mn blade (Fig. 190) with 6 small teeth, decreasing 

 in size dorsally, and minute dorsal seta. 



Mxl gnathobase reduced to 1 or 2 teeth. 



PI as on female, Ri asymmetrical. 



P2 as on female, except Re3 outer spines sharply 

 curved near tip. 



P3-P4 missing Re2-3 on specimens examined; 

 remainder as on female, except B2 outer distal edge 

 without teeth, and Ri2 outer spiniform process re- 

 duced. 



P5 (Fig. 191) nearly reaching distal edge of urosome 

 segment 3. Left Bl reaching one-fourth length of right 

 B2; left B2 reaching one-half length of right Rel. Left 

 and right legs about equal length. Right Re, including 

 terminal blade, slightly longer than left. Order of 

 length, longest to shortest, of Re segments: left 2, 1, 3; 

 right 1 = 2 = 3. Each Rel with short flat seta on outer 



9. Mimocalanus sulcifrons Wheeler, 1970 



(Figures 162, 192-215) 



Mimocalanus nudus. — Grice and Hulsemann, 1965, 



p. 227, fig. 6a-l. Not M. nudus Farran, 1908. 

 Mimocalanus sulcifrons Wheeler, 1970, p. 7-9, fig. 



5-20. 

 Mimocalanus distinctocephalus. — Vidal, 1971, p. 17- 



18, fig. 60-63. Not M. distinctocephalus Brodsky, 



1950. 



Type Specimen: Holotvpe, male (1.90 mm), USNM 

 122646. 



Type Locality: Western North Atlantic, 2,000-4,000 

 m. 



Material StiT)IED: Holotype, male (1.90 mm), sam- 

 ple 45 (Table 3); 3 females (2.20, 2.30, 2.30 mm), sam- 

 ple A26 (Table 1); 3 females (2.24, 2.28, 2.32 mm), 

 sample A48; 4 females (2.05-2.40 mm, mean = 2.23 

 mm), 4 males (2.15-2.60 mm, mean = 2.37 mm), and 

 1 stage V male (2.08 mm), sample A50; 4 females 

 (2.17-2.30 mm, mean = 2.24 mm) and 1 stage V male 

 (2.04 mm), sample A51; 1 female (2.24 mm), sample 

 A52. 



76 



