26 
Mecynocera claust Sars, 1905 (a), p. 2. 
Mecynocera claust Esterly, 1905, p. 137, fig. 16. 
Mecynocera claust Pearson, 1906, p. 8. 
Mecynocera claust van Breemen, 1908, p. 19, fig. 16. 
Mecynocera claus? 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. 37. — 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) ——= Staton (one 
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. perplexus, 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 
recently 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 
Paracalanus 
Paracalanus 
aculeatus Giesbrecht. 
aculeatus Giesbrecht, 1888, p. 333. 
aculeatus Giesbrecht, 1893, p. 164, pl. 9. 
Paracalanus parvus T. Scott, 1893, p. 26, pl. 1, figs. g—14. 
Paracalanus 
Paracalanis 
Paracalanus 
Paracalanus 
Paracalanus 
Paracalanus 
Paracalanus 
Paracalanus 
aculeatus Giesbrecht, 1896, p. 318. 
aculeatus Giesbrecht & Schmeil, 1898, p. 24. 
aculeatus Cleve, 1901, pp. 8 & 47, pl. VI, figs. 1—1I0. 
aculeatus A. Scott, 1902, p. 402. 
aculeatus Cleve, 1903, p. 3606. 
aculeatus Cleve, 1904, p. 194. 
aculeatus Wolfenden, 1905(a), p. 998, pl. XCVI, figs. 12—15. 
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. 
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