14- Family Heterorhabdidae. 

 Genus Heterorhabdus Giesbrecht 1S98. 



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 clausi (Giesbrecht). < 



Heterochaeta clausi Giesbrecht, 1889, p. 812. 

 Heterochaeta clausi Giesbrecht, 1893, p. 372, pi. 20. 

 Heterorhabdus clausi Giesbrecht & Schmeil, 1S9S, p. 115. 

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

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

 Heterorhabdus clausi Esterly, 1905, p. 185, fig. 39. 

 Heterorhabdus 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. 



Hctcrorliabdus clausi resembles Heterorhabdus papilliger in general appearance, but it 

 can readily be distinguished by the antennules extending bevond the furcal joints. Other differences 

 are visible between the appendages of the two species. 



This species has been recorded from the Xorth Atlantic and Pacific Oceans. 



2. Heterorhabdtis spinifrons (Claus). 



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

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

 Heterorhabdus spinifrons Giesbrecht & Schmeil, 189S, p. 114. 

 Heterochaeta spinifrons Wolfenden, 1902, p. 362. 

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

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

 Heterorhabdus spinifrons Geve, 1904, p. 191. 

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

 Heterorhabdus spinifrons Farran, 1905, p. 44. 

 Heterorhabdus spinifrons Esterly, 1905, p. 183, fig. 37. 

 Heterorhabdus spinifrons Pearson, 1906, p. 27. 

 Heterorhabdus spinifrons Esterly, 1906, p. JJ. 

 Heterorhabdus spinifrons Farran, 190S, 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 followine stations. 



1 3° 



