Mxl gnathobase with 3 proximal setae [Park (1970, 

 fig. 17) shows 4) on posterior surface; without seta on 

 distal anterior surface. 



Mx2 with moderately strong, setule-covered hump 

 on proximal outer edge; outer seta present; posterior 

 surface of lobe-5 base with spines. 



Mxp (Fig. 6) Bl without spine-comb; longitudinal 

 row of stiff hairs on midanterior surface; outer edge 

 with 2-3 clusters of short setules. Transverse spine- 

 comb of 6-7 moderate spines present or not on B2. B2 

 with longitudinal row of stiff hairs. Two outer setae on 

 Ri4-5 nude, bladelike, tapering toward each end; 

 spinules on inner edge of terminal Ri5. 



PI (Fig. 7) Bl surface with few setules; inner 

 margin with hairs. B2 surface with few setules and 

 hairs; inner margin with hairs. Rel anterior surface 

 with outer distal row of spinules; Re2 surface nude; 

 Re3 posterior surface with 0-4 spines. Rel outer spine 

 reaching to or beyond base of Re2 outer spine; Re2 

 outer spine reaching beyond base of Re3 outer spine. 

 Ri surface nude. 



P2 (Fig. 8) Bl surface nude or with few setules, in- 

 ner margin with hairs. P3 (Fig. 9) Bl surface with few 

 setules, inner margin with hairs. P4 (Fig. 10) Bl sur- 

 face with few thin setules in addition to posterior 

 transverse row; inner margin with hairs; B2 nude. 



Re2 posterior surface on P3 with proximal row of 

 ca. 8 very broad, flat, leaflike spines and distal row of 

 5-6 denticles; on P4 with proximal row of ca. 9 sim- 

 ilar leaflike spines and distal row of ca. 6 small 

 spines. 



Re3 posterior surface on P2 with 3 rows of 2-4 spines 

 each; on P3 without proximal row of spines, but with 2 

 distal rows of a few small spines; on P4 with 3 rows of 

 up to 5 small spines. 



P3 Ri3 posterior surface with 2 rows of spines. 



Re terminal seta with following number of primary 

 teeth: P2 (24-38); P3 (27-34); P4 (25-29). P2 terminal 

 seta slightly longer than Re3; P3 terminal seta 

 somewhat shorter than Re3. 



Male.— -Length 0.90-1.2 mm. Prosome anterior 

 irregular in dorsal view, posterior somewhat rounded; 

 in lateral view with gentle forward slope. Ce and Thl 

 partly fu.sed. Prosome length 2 times urosome. Caudal 

 rami length slightly more than width, symmetrical. 

 Caudal setae unknown. 



Al reaching about end of Th4. 



P4 Bl proximal outer surface with setules; without 

 inner seta. 



P5 biramus, left-handed; left Bl reaching one-third 

 length of right B2; left B2 reaching middle of right 

 Rel. Left leg longest; left Re (including terminal 

 blade) longest; right Ri longest. Order of length, 

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

 = 2, 3. Left Ri reaching middle of left Re2; right Ri 

 reaching middle of longest terminal seta of right Re. 

 Each Re with 1 small and 1 moderate bladelike ter- 

 minal setae. 



Remarks 



Giesbrecht (1888, 1892) examined "about a half- 

 dozen" mutilated females on which he based his 

 description of the first Spinocalanus species, 6'. 

 abyssalis. He did not illustrate the prosome; his 

 figures of appendages, characteristically excellent, 

 differentiated .S. abyssalis from the other 

 Pseudocalanidae with which it was placed. However, 

 the lack of information on body form and probably 

 also the lack of a figure of P2 (even though Giesbrecht 

 stated that P2 Ri2 had only 4 setae) led subsequent 

 investigators to unite more or less closely related 

 species with S\ abyssalis. It is a curious coincidence 

 that Sars (1900) mi.stakenly illustrated P2 Ri2 of Arc- 

 tic iS'. longicornis with 5 setae (rather than 4), and 

 later (1903) mistakenly illustrated the same segment 

 on Norwegian .S. brevicaudatus with 4 setae (rather 

 than 5). Sars also failed to illustrate the surface spines 

 of the swimming legs of S. brevicaudatus, and when 

 he claimed that these three species were identical, it 

 became effectively impossible to reconcile the 

 descriptions solely from the literature. 



Farran (1926) proposed Spinocalanus abyssalis var. 

 pygmaeus for the smaller of at least two forms, 

 thereby making the larger form the "typical" species, 

 even though Giesbrecht 's specimens were small. This 

 was repeated by most investigators and served to 

 further confound the concept of "Spinocalanus 

 abyssalis." 



Specimens examined in this study agreed essential- 

 ly with the description and figures of Giesbrecht 

 (1892). Giesbrecht's unit in measuring Al segments 

 should have read 0.005 mm, not 0.05 mm. The Mxp he 

 illustrated lacked the fragile outer seta on Ri4. 

 Giesbrecht stated that PI Re3 posterior surface may 

 or may not have spines, though the illustrated PI 

 lacked these spines. 



References to S. abyssalis by Giesbrecht and 

 Schmeil (1898), van Breemen (1908, part), and 

 Brodsky (1950) are solely repetitions of the work of 

 Giesbrecht (1892). 



Thompson (1903) illustrated P5 of a juvenile male 

 from the west of Ireland; no size was reported. The 

 figure does not agree with P5 of male stage V S. 

 longicornis (see Fig. .34) or S. brevicaudatus (With, 

 1915, fig. 15e). Thompson's specimen could be S. 

 abyssalis, although possibly it is not even a 

 Spinocalanus species. 



Park's (1970) description and figures of S. abyssalis 

 agree with Pacific specimens and include the first 

 habitus illustrations of this species. 



Grice's (1971) figures also agree with the description 

 of S. abyssalis. The references to these figures are cor- 

 rect in his key, but the figure legend transposed the 

 caption for ^S. abyssalis and .S\ parabyssalis (G. Grice, 

 pers. commun.). 



Farran's (1926) first use of S. abyssalis var 

 pygmaeus referred at least to .S. longicornis, but 

 possibly also to S. abyssalis since both species occur in 



19 



