26 



Mecynocera clausi Sars, 1905 (a), p. 2. 



Mecynocera clausi Esterly, 1905, p. 137, fig. 16. 



Mecynocera clausi Pearson, 1906, p. 8. 



Mecynocera clausi van Breemen, 1908, p. 19, fig. 16. 



Mecynocera clausi although not common in any of the 'Siboga' plankton samples, had 

 a moderately wide distribution in the area investigated, as shewn by the following records. 



■ 



Stat. 16. — Stat. 19. — Stat. 35. — Stat. 36. — Stat. 17. — Stat. 40. — Stat. 47''. — 

 Stat. 96 (day). — Stat. 96 (night). — Stat. 98. — Stat. 101. — Stat. 106. — Stat. 109. — 

 Stat. 121. — Stat. 141. — Stat. 143. — Stat. 144. — Stat. 146. — Stat. 148. — Stat. 

 184. — Stat. 203 (surface). — ■ Stat. 203 (1500 metres). — Stat. 213. — Stat. 217 (hori- 

 zontal cylinder). — Stat. 220 (vertical net) — Stat. 252. — Stat. 276. — Stat. 282. — 

 Stat. 304. — Stat. 315. 



This Calanoid has been recorded from the Mediterranean, Atlantic, Indian, and Pacific Oceans. 



3. Family Paracalanidae. 

 Genus Paracalanus Boeck, 1864. 



The known Calanoids belonging to this genus are small and rather robust. The females 

 can be readily recognised by the presence of a small fifth pair of feet. The fifth feet of the 

 female is composed of a basal part and one free joint. A form described by Canon Norman 

 and T. Scott as Paracalanus parvus, var. pcrplcxtts, differs from the typical members of the 

 genus, in that the left fifth foot of the female has two free joints instead of one. I have 

 reeen tly detected this variety in plankton from the Irish Sea, but whether it is normal or not, 

 is difficult to make out, as the material is very limited. The right fifth foot of the males of 

 Paracalanus is the same as in the female. The left foot is elongated and slightly prehensile, 

 with four free joints. The largest size that any of the females attain appears to be 1,2 mm. 



Two species were represented in the plankton collected by the 'Siboga'. 



1. Paracalanus aculeatus Giesbrecht. 



Paracalanus aculeatus Giesbrecht, 1888, p. 333. 



Paracalanus aculeatus Giesbrecht, 1S93, p. 164, pi. 9. 



Paracalanus parvus T. Scott, 1893, p. 26, pi. 1, figs. 9 — 14. 



Paracalanus aculeatus Giesbrecht, 1896, p. 318. 



Paracalanus aculeatus Giesbrecht & Schmeil, 1898, p. 24. 



Paracalanus aculeatus Cleve, 1901, pp. 8 & 47, pi. VI, figs. 1 — 10. 



Paracalanus aculeatus A. Scott, 1902, p. 402. 



Paracalanus aculeatus Cleve, 1903, p. 366. 



Paracalanus aculeatus Cleve, 1904, p. 194. 



Paracalanus aculeatus Wolfenden, 1905 (a), p. 998, pi. XCVI, figs. 12 — 15. 



Paracalanus aculeatus Sars, 1905 (a), p. 2. 



Paracalanus aculeatus appeared to have a wide distribution throughout the region traversed 

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



26 



