COPEPODA 



75 



I have preferred to exclude other species of somewhat doubtful position, as well as to let Wolf - 

 enden's genus Mesundeuchceta go out. Though the different species of Euchirella differ from 

 each other in several important features, I think the genus is a quite natural one, as it is not only 

 characterized by the structure of the antennae and maxillulae, but also by the presence of a glandular 

 pore at the base of Se I Re II pes II— IV (cf. Chiridius), which is wanting in the penultimate stage. 

 In Euch. rostrata, messinensis, maxima and betumida a glandular pore is wanting in the first outer 

 segment in the second pair of legs, but in E. curticaiida and intermedia it is wanting in the third 

 and fourth pairs of legs as well. In addition to the generally accepted specific characters, good ones 

 are found in the structure of the oral surface of the labrum, in the number of bristles of the exopodite 

 of the maxillulae in the males, and in the marginal hairs of the second basipodite of the fourth 

 pair of legs. 



15. Aetidius armatus Boeck. 

 (PI. II fig. 1 a— d; text-fig. 16). 



1904. Aetidius tenuirostris n. sp. Wolfenden, pp. 116 — 117. 



1872. Pseudocalanus armatus n. sp. Boeck, p. 38. 



18S3? Aetidius armatus 11. sp. Brady, p. 75. 



1892. nee. — — Brady. Giesbrecht, p. 213, taf. 2, 14 



and 36. 

 1S93. pars. — — — Th. Scott, p. 70. 



1898. pars. — — — Giesbrecht & Schmeil, p. 31. 



1901. — Boeck. Th. Scott, p. 238. 



1902. — — Th. Scott, p. 451. 



1902. — — G. O. Sars, pp. 25 — 26, pis 



XIII— XIV. 



1903. — — Norman, p. 136. 



1903. — Jensen, Johansen, Tevinsen, 



p. 304. 

 1903 ? — — Brady. J. C. Thompson, p. 16. 



i9°5 

 I9°5 

 i9°5 

 1906 

 1908 

 1908 

 1909 

 1909 



1910, 

 1910 

 1911 



armatus Boeck. Farran, p. 31. 



— Esterly, p. 145, figs. 14 a— b. 

 Th. Scott, p. 222. 



— Pearson, p. 11. 



— v. Bremen, p. 30 fig. 30. 



— Farran, p. 28. 



— Pesta, p. 23. 



— A. Scott, pp. 37- 38, pi. IV, figs 



14-25. 



— Steuer, pp. 23 — 24. 



— Wolfenden, p. 209, text-fig. 4. 

 — — Farran, pp. 81—82. 



Description. £. Size of specimen from Ingolf St. 47, 1-93 mm.: anterior division (head -|- som. 

 thor. I 0-920; somite II— V 0-575) r 495! urosome 0-437 mm. 



The head is as figured by Sars etc. vaulted in a characteristic way without frontal keel, and 

 the rostrum has two pointed branches without basal tubercle. The genital somite, which is both wider 

 and deeper than long, has a receptaculum seminis (text-fig. 16) which is distinctly dif- 

 ferent from that of A. Giesbrechtii CI eve 1904 (synonymous with A. mediterraneus 

 Steuer 1910), as seen by comparing figs 1 a— b with Giesbrechts fig. 9 Taf. 36; the 

 vulva (fig. ib) is also somewhat different from Giesbrecht's fig. 8. 



The measurements of the antennulae are distinctly different from those given 

 by Giesbrecht, as the segment 23 is shorter than 22, and as segment 24^25 is 

 respectively 1-4 and 1-5 as long as segment 8^9 and 2 (not 2 and 2-5). The antennae 

 differ from Sars' as well as from Giesbrecht's figures by the small process on which 

 the proximal seta of Re II is placed. The other mouth appandages show some dif- 

 ferences from Sars' figures, but not in any feature worth to be mentioned from Gies- 

 brecht's description. 



The pes I differs from Giesbrecht's description (fig. 10) by the second basipodite, which has 

 no setae exteriorly and distally, and by the third one, which has no spinous area laterally and anteriorly. 



Text-fig. 16. 



Aetidius armatus 



Boeck. 



Abdomen in left 



view X 57- 



