j x g COPEPODA 



32. Euchirella curticauda Giesbrecht. 

 (PI. IV figs 3a — m; PI. VIII, figs 2 a — c; text-figs 29 a — e.) 



1888. Euchirella curticauda n. sp. Giesbrecht, p. 336. 



1892. — — Giesbr. Giesbrecht, p. 233, taf. 15, 36. 



1898. — Giesbrecht & Schrueil, p. 36. 



1902. — — J. C. Thompson, p. 18. 



1904? — — var. atlantica n. var. Wolf- 



enden, p. 116. 



1905? atlantica n. sp. Wolfenden, p. 20. 



1905. curticauda Giesbr. G. O. Sars, p. 4. 



1905. Euchirella curticauda Giesbr. Farran, p. 35. 



1906. — — Esterly, p. 59, pes 9, 10, 



12—13. 



1906. — — — Pearson, p. 15. 



190S. — — — v. Bremen, p. 48, fig. 54. 



1908. — — Farran, p. 38. 



1909. — A. Scott, p. 55. 

 1911. — — Wolfenden, p. 236. 



Description. f<j>. Size: Specimen from Thor St. 88 4-26 mm.; anterior division measured 3-61 mm.; 

 urosome 0-65 mm. Gie'sbrecht's specimen measured 3-5, Farran's 4-3 — 4-8. 



The head has a prominent rounded frontal keel (PI. IV fig. 3 a); the frontal organ is fairly pro- 

 minent at the base of a low prolongation downwards from the keel; the rostrum, which is only visible 

 from beneath, is short and undivided, but sometimes asymmetrical with an accessory tooth on the right 

 side. The articular membrane between the head and the first thoracic tergite is indicated in some spec- 

 imens, but is completely wanting in others. The posterior margin of the first to fourth tergites is 

 strongly chitinized, and falls on each side naturally into a lateral and two median divisions; behind the 

 hinder margin of the fourth tergite and partly covered by it, the fifth thoracic tergite, hollowed like a 

 gutter, is found. The cephalosome is about 6-5 as long as the abdomen. The genital somite is distinctly 

 produced below, and has, on each side of the vulva, a lateral projection, generally visible from the side; 

 along the hinder margin of this somite is a marginal seam. The antennulae almost reach to the end of 

 the genital somite, the appendages are as in E. messinensis, but the measurements are distinctly different, 

 as the distal segments are comparatively shorter; the 8029. segments, f. inst, are about as long as seg- 

 ment 15, not much shorter. The antenna is in its main features like Giesbrecht's fig. 3 Taf. 15, but 

 a distinct articulation is found between Re I and Re II. The maxillulae stand as pointed out by Gies- 

 brecht, between E. rostrata and messinensis; the Le 1 has 9 setae, but the Li 1 has, as in messinensis, 

 only 3 posterior setae, and the Li 2 4 strong setae; the Li 3 and basipodite 3 are also like this species, 

 but the Ri has 3 setae only. The maxillipes has, exteriorly, near the tip of the anterior surface of the 

 second basipodite, as mentioned by Giesbrecht, a characteristic knob-formed process. 



The margin between Se 1 — 2 of Re I <n> n in the first pair of legs is only slightly concave, with 

 a minute pore. The pes II (text-fig. 29 a), which has 26 teeth in the St., has a well developed first Se 

 in Ri, and the same number of secretory pores as in the preceding species. The pes III has a distinct 

 accessory tooth at the base of Se Ri I ; the glandular pore in Re I seems to be wanting (text-fig. 29 b). 

 The number of spines interiorly on the posterior surface of basipodite II in pes IV varies from 7 to 13, 

 and is most often different on the two sides; the accessory tooth of Se Ri I is smaller; the secretory 

 pore in the Re I is sometimes indicated. 



The anterior surface of the labrum is like that of E. rostrata. The chitinous system which 

 supports the oral surface of the labrum attains a characteristic development, as seen in fig. 3 c, as 

 the anterior bars are directed towards the middle, almost touching each other, and almost encircling the 

 median circular spot Nr. 3. The groups of setae in the longitudinal series show a characteristic ar- 

 rangement: the first group consists of an area covered with about 30 short strong spines; the 



