12 2 



This species has been found to be widely distributed. I have seen examples obtained 

 from the deep water of the Faröe Channel. 



5. Metridia venusta Giesbrecht. Plate XXXYII, figs. 15 — 20. 



Metridia venusta Giesbrecht, 1889, p. 24. 



Metridia venusta Giesbrecht, 1893, p. 340, pi. n (female). 



Metridia normani Giesbrecht, 1893, p. 340, pi. 33 (male). 



Metridia venusta Giesbrecht & Schmeil, 189S, p. 107. 



Metridia normani Giesbrecht & Schmeil, 1898, p. 107. 



Metridia normani Wolfenden, 1904, p. 125, pi. IX, fig. 39. 



Metridia venusta Cleve, 1904, p. 192. 



Metridia venusta Farran, 1905, p. 43. 



Metridia venusta Pearson, 1906, p. 23. 



Metridia venusta Farran, 1908, p. 60. 



Metridia venusta van Breemen, 1908, p. 110, fig. 126. 



Metridia normani van Breemen, 1908, p. 109, fig. 125. 



Twelve females and six males belonging to the above species were found in the plankton 

 collected, with one exception, by means of the Hensen vertical net at the following stations. 



Stat. 118 (900 metres to surface), 2 specimens. — Stat. 128 (700 metres to surface), 3 spe- 

 cimens. — Stat. 141 (1500 metres to surface), 3 specimens. — ■ Stat. 142, 1 specimen. — 

 Stat. 143 (1000 metres to surface), 4 specimens. — Stat. 148 (1000 metres to surface), 

 2 specimens. — Stat. 203 (1500 metres to surface), 2 specimens. — Stat. 276 (750 metres 

 to surface), 1 specimen. 



The two sexes of this Metridia can readily be recognised by the asymmetrical furcal 

 joints. The right furcal joint is distinctly shorter than the left. The fifth pair of feet of the 

 female, consists of one free joint attached to a basal part. Length, female 3,1, male 2,8 mm. 



I do not think that there can now be any doubt that the species described by Giesbrecht 

 as Metridia normani, is only the male of Metridia venusta. The male fifth pair illustrated in 

 this report is identical with the figure given by Giesbrecht. Wolfenden' s figure of the fifth 

 pair of the supposed female of Metridia normani is simply the fifth pair of the female of 

 Metridia venusta. If a line be drawn across from the outer edsre setae to the inner margin 

 in the figure now given, one would practically have a similar illustration to that shewn by 

 Wolfenden. The joint shewn by that author is probably due to a defective prepara tion. 

 Giesbrecht's figure of the female fitth pair, shews the apex of the free joint to be furnished 

 with two setae. The 'Siboga' females have three as illustrated. (Plate XXXVII, fig. 17). 



Metridia venusta has a distribution almost similar to that of Metridia princeps. 



Genus Pleuromamma Giesbrecht, 1898. 



The members of this genus are readily recognised by the presence of a pigmented 

 luminous organ on the right or left side of the first thoracic segment. 



Three species were represented in the area traversed by the 'Siboga'. 



1 . Pleuromamma abdominalis (Lubbock). 



Diaptomus abdominalis Lubbock, 1856, p. 22, pi. X. 



