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male fifth pair has a two-jointed basiopodite and exopodite. The exopodite of the right foot 

 is prehensile as in the other genera belonging to the family. 



The members of this genus that are already known have no side hooks on the cephalic 

 segment. A species that appears to be undescribed was obtained from the 'Siboga* plankton, 

 and although it agrees quite well with Calanopia in the structure of its appendages, the cephalic 

 segment is provided with side hooks. 



Four species were represented in the plankton collected during the traverse in the Malay 

 Archipelago. Two of the species do not appear to have previously been describecl. 



Illustrations of two other known forms, that were not obtained from the plankton collected 

 by the 'Siboga', are included in this report, in order that the differences between the six species 

 of Calanopia now known can clearly be observed. 



1. Calanopia elliptica (Dana). Plate XLVIII, figs. 1 — 5. 



Pontclla elliptica Dana, 1849, p. 27. 



Calanopia elltptica Dana, 1852, p. 1132, pi. 79. 



Calanopia elliptica Brady, 1883, p. 85, pi. XXXIV, figs. 1 — 9. 



Calanopia elliptica Giesbrecht, 1893, p. 441, pis. 31 & 38. 



Calanopia elliptica Giesbrecht, 1896, p. 325, pi. 5, figs. 7 — 9. 



Calanopia elliptica Giesbrecht & Schmeil, 1898, p. 132. 



Calanopia elliptica I. C. Thompson, 1900, p. 282. 



Calanopia elliptica Cleve, 1901, p. 5. 



Calanopia elliptica A. Scott, 1902, p. 406. 



Calanopia elliptica Thompson & Scott, 1903, p. 251. 



Calanopia elliptica Cleve, 1903, p. 356. 



Calanopia elliptica Wolfenden, 1905 (a), p. 1023. 



This species is the type of the genus. It was well distributed throughout the area 

 investigated by the 'Siboga', as shewn by the following records 



Stat. 16. -- Stat. 35. — Stat. 36. — Stat. 37. — Stat. 47". — Stat. 66. — Stat. 71. — Stat. 

 75 (HENSEN vertical net, 11 metres to surface). — Stat. 81. — Stat. 96 (day). — Stat. 98. • — 

 Stat. 99. — Stat. 109. — Stat. 117*. — Stat. 125 (day). — Stat. 128 (HENSEN vertical 

 net, 900 metres to surface). — Stat. 136. — Stat. 138. — Stat. 141 (HENSEN vertical net, 

 1500 metres to surface). — Stat. 142. — Stat. 143 (HENSEN vertical net, 1000 metres to 

 surface). Stat. 144. — Stat. 148 (HENSEN vertical net, 1000 metres to surface). — Stat. 149. — 

 Stat. 165. - - Stat. 174. -- Stat. 184. — Stat. 185 (HENSEN vertical net, 1536 metres to 

 surface). -- Stat. 205. — Stat. 213. — Stat. 215". — Stat. 216. — Stat. 223. — Stat. 229. — 

 Stat. 245. -- Stat. 271 (horizontal cylinder). — Stat. 276 (HENSEN vertical net, 750 metres 

 to surface). — Stat. 304. — Stat. 315. 



Examples of this species were not numerous in any of the collections except the one 

 from Station 142. This was a night gathering, and 1241 specimens were obtained from the 

 sample. This number was represented by 268 females and 973 males. 



Length of female, 1,9 mm. 



The combined length of the abdomen and furca is contained nearly twice in the total 

 length of the cephalolhorax, from the frontal margin to the base of the genital segment. The 

 second abdominal segment is about as long as the genital segment. It is three trmes longer 

 than broad. The furcal joints are nearly three times longer than broad. 



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