231 
Setella gracilis Brady, 1883, p. 108, pl. L, figs. 1—10. 
Setella gracilis Giesbrecht, 1893, p. 559, pls. 1 & 43. 
SAUTE BEGINS Ws SCO, WOK, jd4 3Kore). 
Setella gracilis 1. C. Thompson, 1900, p. 285. 
Setella gracilis Wheeler, 1900, p. 188, fig. 24. 
Setella gracilis Cleve, 1901, p. 9. 
Setella gracilis A. Scott, 1902, p. 409. 
Setella gracilis 1. C. Thompson, 1903, p. 33. 
Setella gracilis Thompson & Scott, 1903, p. 257. 
Setella gracilis Cleve, 1903, p. 368. 
Setella gracilis Wolfenden, 1905 (a), p. 1030. 
Setella gracilis van Breemen, 1908, p. 178, fig. 192. 
Males and females belonging to this characteristic form were obtained from the plankton 
collected at the following stations. 
SO Med ESO tdta 30-1 Stat. 37. — Stat. 40. —- Stat. 47, —) Stabeson == 
stat. 66. — Stat. 75 (11 metres to surface). — Stat. 81. — Stat. 96 (night). — Stat. 98. — 
idiom Staab Ton (QOOmmeties to Surface), —— Stat. 121 ——) Stateui240—— 
Stat. 128 (700 metres to surface). — Stat. 138. — Stat. 143 (1000 metres to surface). — 
Stat. 146, — Stat. 148 (1000 metrés to surface). — Stat. 168. — Stat. 213. — Stat. 216-— 
Stat. 217. — Stat. 304. — Stat. 315. 
Macrosetella gracilis appears to be an entirely pelagic species and has a moderately 
wide distribution in the warm regions of the great oceans. 
38. Family CLyTEMNESTRIDAE nov. 
The body is rather slender and depressed. The distal ends of the cephalic and first 
three thoracic segments are considerably expanded and pointed. The thoracic segments are 
produced posteriorly. The cephalic segment is large and triangular in outline when seen from 
above, and is furnished with a blunt pointed rostrum. The antennules are eight-jointed. The 
exopodite of the antennae is short and one-jointed. The mandibles, maxillae and first pair 
of maxillipedes are very rudimentary. The second pair of maxillipedes is well developed and 
prehensile. The exopodite of the first pair of feet is composed of a single joint. The endopodite 
is three-jointed and much longer than the exopodite. The exopodites and endopodites of the 
second, third and fourth pairs of feet are three-jointed. The fifth pair of feet is slender and 
two-jointed. The female carries a single ovisac. 
This family is established for the reception of the genus C7lylemmnestra Dana. It differs 
very considerably from any of the other Harpacticoida in the long-jointed prehensile second 
pair of maxillipedes, and in the structure of the first pair of feet. + 
Genus Clytemnestra Dana, 1852. 
The members of this genus are easily recognised by the form of the body, by the 
pointed cephalic and thoracic segments, and by the structure of the various appendages. 
231 
