﻿COPEPODA 



89 



23. Gaidius tenuispinus G. O. Sars. 

 (PI. II fig. 8 a; pi. Ill fig.s 2 a— n; text-fig.s 23 a— j). 



1900. Chiridius tenuispinus n, sp. G. O. Sars, p. 67, pi. X\'1II. 

 1902. Gaidius tenuispinus G. O. Sars. Mriizek, p. 512. 



1902. — borealis n. sp. Wolfenden, p. 365. 



1903. — tenuispinus (1. O. vSars. Nonnan, p. 136. 



1903. Chiridius tenuispinus G. O. Sars. G. O. Sars, pp.30 — 31, 



pi. XVIII. 



1903. Gaidius tenuispinus G. O. Sars. G. O. Sars, p. 162, pi. VI, 



suppl. 



1904. ?Gaidius pungens Giesbr. Wolfenden, p. 131, pi. IX fii;. 43, 



1905. Chiridius tenuispinus G. O. Sars. Th. Scott, p. 223. 



1905. Gaidius tenuispinus G. O. Sars. Farran, p. 33. 



1906. — — — Pearson, p. 13. 



1907. Gaidius tenuispinus (5. 0. Sars. Vanluiffcn, pp. 521— 522, 



taf. 21 fiji. 27, taf. 22 fig. 33. 

 1907- - — G. O. Sars. Koefoed & Danias, p.408. 



190S. — — — I'arran, p. 32. 



190S. — - - - V. Bremen, p. 36, fig. 39. 



1909. Nee. — siniilis Tli Scott. A.Scott, pp. 51— 52, pi. VII 



figs III. 

 19' I- — tenuispinus G. O. Sars, I'arran, p. 97. 



191 1? — — — Wolfenden, p. 223, figs 



1 1 a--b. 

 19' 3- — — — Stephcnsen, pp. 315 



-3i6. 



Description. f5>. vSize: vSpL-ciinen from Thor vSt. 70 iiiea.surcd 3-84 niiii.; anterior divi.sioii 2-94 luin.; 

 urosome o-go iniii. Two specimeii.s from Thor vSt. 285 mea.sured 2-6 + 0-62 = 3-22 mm. and 2-9 ~ oS 

 = 37 mm.; specinien.s from Thor vSt. 1S3 measnred 27+07 = 3'4 nil"- Sars' .specimens measured 3-8 

 and Wolf en den's 3-8(1904) and 3-25 (191 1) mm. Van ho f fen's specimens 3-9 and Farran's (1905) 3-2 mm. 



The shape of the body is scarcely different from vSars' figure, and no trace of segmentation 

 between the fourth and fifth thoracic somite was observed; the lateral spines of the thorax are distinctly 

 set off, and extend almost to the end of the genital somite (text-fig. 23 a). The rostrum is not, as set 

 forth by most authors, undivided, but shows as seen in fig. 2 a (PI. Ill) trace of bifurcation. 



The length of the abdomen, compared to that of the anterior divi.sion, varies from about ■/, 

 to '/4- The genital somite, which as seen in fig. has a short and well marked receptaculuni semini.s, 

 well distinguished from the stalked one in Cliiridius, is somewhat deeper and wider than long, and 

 1-6 as long as the third siMiiitc. The furcal rami are i-6 as long as wide and a little wider than the 

 anal somite is long. 



The iintonuilac reach to about the end of the third abdominal somite and have the measure- 

 ments distinctly different from those of (i. hre7<ispiiius on account of the shorter distal segments; the 

 segment 2 is 1-2 as long as 8^9, which is almost 1-3 as long as segment 13 and only a little shorter 

 than segment 20; the segments 19 and 22 are almost of equal length, and almost ri shorter than 

 segment 2. The appendages are like those described bv Giesbreclit in Gactdiiiis arniigcr with 

 "Aesthetasken" in segments 3, 4 and 6 and Spr. in segment 13; the posterior seta of the segment 23 

 is ringed, and about three times as long as the segments 24 and 25, which are well separated. 



The aiiti-)i)iar have the Re 1-3 as long as Ri; the Ri I is distincth- twice as long as Re II; 

 this is about twice as long as Re I, and about twice as long as Re III — YI, and about - ; as long as 

 Re VII. The Re II has the short Se 2 placed on a rather ]>roniineut process, (PL III fig. 2 e), like 

 that found in (liesbrech t's fig. 19 Taf. 14 of (iiirfm/iis ariiii»ii\ and the Se 3 is somewhat longer. 

 The iiiaiidihuliu- differ from vSars' figure by two slender vSi of the third basipodite, and are in main 

 features like those in ( li esbrech t's (}. uniiii^rr. The iinixiUiilar are rather elongated, like Gies- 

 brecht's figure of Gactainis iiiiirs (Taf. i.| fig. 21); tl'.e Li I pcsscsses on the anterior surface about 10 

 fairly strong teeth, and on the posterior surface near the base of vS 1 1 about 10 similar ones; the Li II 

 has 4 .setae, and the Li III 5 | a sensory lobe and anteriorh' a fairly strong spinulation, the Pasj). Ill 



Tllc Iiif^olf-Expciiition. HI. 4. '* 



