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Stat. 66, i specimen. - ■ Stat. 141 (Mensen vertical net, 1500 metres to surface), 2 speci- 

 mens. - Stat. 143 (MENSEN vertical net, 1000 metres to surface), 1 specimen. - - Stat. 

 148 (HENSEN vertical net, 1000 metres to surface), 1 specimen. Stat. 1 S 5 (HENSEN 



vertical net, [536 metres to surface), 2 specimens. -- Stat. 203 (HENSEN vertical net, 1500 

 metres to surface), 2 specimens. - - Stat. 217 (horizontal cylinder), 1 specimen. Stat. 



220 (HENSEN vertical net, 200 metres to surface), 1 specimen. — Stat. 243 (HENSEN vertical 

 net, 1000 metres to surface), 2 specimens. - ■ Stat. 276 (HENSEN vertical net, 750 metres 

 to surface), 1 specimen. — ■ Stat. 304, 1 specimen. -- Stat. 315, 1 specimen. 



Heterorhabdus spinifrons can readily be separated from the other members of the genus 

 by the rostral papilla ending in sharp points, and by the strong curved spine on the upper 

 surface of the first basal joint of the second pair of maxillipedes. 



This species has apparently a moderately wide distribution in the great oceans. 



3. Heterorhabdus longicornis (Giesbrecht). 



Heter ocliaeta longicornis Giesbrecht, 1889, p. 812. 

 Heterochaeta longicornis Giesbrecht, 1893, p. 373, pis. 20 & 39. 

 Heterorhabdus longicornis Giesbrecht & Schmeil, 1898, p. 116. 

 Heterorhabdus longicornis I. C. Thompson, 1903, p. 27. 

 Heterorhabdus longicornis Wolfenden, 1904, p. 112. 

 Heterorhabdus longicornis Sars, 1905 (b), p. 3. 

 Heterorhabdus longicornis Farran, 1905, p. 45. 

 Heterorhabdus longicornis Esterly, 1905, p. 186, fig. 40. 

 Heterorhabdus longicornis Pearson, 1906, p. 26. 

 Heterorhabdus longicornis Esterly, 1906, p. yy. 

 Heterorhabdus longicornis Farran, 1908, 6y. 

 Heterorhabdus longicornis van Breemen, 1908, p. 125, fig. 144. 



Eight females and three males belonging to this species were found in the plankton 

 collected at the following stations. 



Stat. 128 (HENSEN vertical net, 700 metres to surface), 1 specimen. — Stat. 141 HENSEN 

 vertical net, 1500 metres to surface), 2 specimens. -- Stat. 143 (HENSEN vertical net, 1000 

 metres to surface), 2 specimens. — Stat. 148 (HENSEN vertical net, 1000 metres to surface), 

 2 specimens. — Stat. 203 (HENSEN vertical net, 1500 metres to surface), 1 specimen. - 

 Stat. 243 (HENSEN vertical net, 1000 metres to surface), 2 specimens. — Stat. 276 (HENSEN 

 vertical net, 750 metres to surface), 1 specimen. 



This species is readily distinguished from the other members of the genus by its very 

 long antennules. The antennules extend beyond the end of the furca by eight or nine joints. 

 The distribution appears to be very similar to that of Heterorhabdus spinifrons. 



4. Heterorhabdus papilliger (Claus). 



Heterochaeta papilligera Claus, 1863, p. 182, pi. XXXII. 

 Heterochaeta papilligera Giesbrecht, 1893, p. 372, pis. 20 & 39. 

 Heterorhabdus papilliger Giesbrecht & Schmeil, 1898, p. 114. 

 Hererochaeta papilligera Cleve, 1901, p. 7. 

 Heterorhabdus papilliger I. C. Thompson, 1903, p. 27. 

 Heterorhabdus papilliger Thompson & Scott, 1903, p. 249. 



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