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14. Family HrTerorRHABDIDAE. 
Genus Heterorhabdus Giesbrecht 1898. 
The members of this genus are distinguished by the asymmetrical furcal joints, and by 
the long second inner setae on the left furcal joint. 
Four species were represented in the plankton collected during the investigations carried 
out in the Malay Archipelago by the ‘Siboga’. 
1. Heterorhabdus claust (Giesbrecht). 
FHeterochaeta clausi Giesbrecht, 1889, p. 812. 
Heterochaeta clausi Giesbrecht, 1893, p. 372, pl. 20. 
Heterorhabdus clausi Giesbrecht & Schmeil, 1898, p. 115. 
Fleterorhabdus claust 1. C. Thompson, 1903, p. 27. 
Heterorhabdus claust Thompson & Scott, 1903, p. 249. 
Fleterorhabdus claust Esterly, 1905, p. 185, fig. 39. 
Fleterorhabdus clausi van Breemen, 1908, p. 122, fig. 140. 
Two females and one male belonging to this species were found in the plankton collected 
with the HENSEN vertical net at the following stations. 
Stat. 128 (700 metres to surface), 1 female. — Stat. 148 (1000 metres to surface), 1 male. — 
Stat. 276 (750 metres to surface), 1 female. 
Fleterorhabdus claust resembles Feterorhabdus papilliger in general appearance, but it 
can readily be distinguished by the antennules extending beyond the furcal joints. Other differences 
are visible between the appendages of the two species. 
This species has been recorded from the North Atlantic and Pacific Oceans. 
2. Heterorhabdus spinifrons (Claus). 
FHeterochaeta spinifrons Claus, 1863, p. 182, pl. XXXII. 
Heterochaeta spinifrons Giesbrecht, 1893, p. 372, pls. 20 & 309. 
Fleterorhabdus spinifrons Giesbrecht & Schmeil, 1898, p. 114. 
Heterochaeta spinifrons Wolfenden, 1902, p. 362. 
Heterorhabdus spinifrons 1. C. Thompson, 1903, p. 27. 
Heterorhabdus spinifrons Thompson & Scott, 1903, p. 249. 
Fleterorhabdus spinifrons Cleve, 1904, p. IQl. 
FHeterorhabdus spinifrons Sars, 1905 (6), p. 3- 
Heterorhabdus spinifrons Farran, 1905, p. 44. 
Fleterorhabdus spinifrons Esterly, 1905, p. 183, fig. 37. 
FHeterorhabdus spinifrons Pearson, 1906, p. 27. 
Heterorhabdus spinifrons Esterly, 1906, p. 77. 
Fleterorhabdus spinifrons Farran, 1908, p. 65. 
Heterorhabdus spinifrons van Breemen, 1908, p. 119, fig. 137. 
Sixteen specimens identical with the above species were obtained from the plankton 
collected at the following stations. 
130 
