Two species are at present known. One was represented in the plankton collected by 

 the 'Siboga' in the Malay Archipelago. 



i. Clytemnestra rostrata (Brady). 



Goniopsyllus rostratus Brady, 1883, p. 107, pi. XLII, figs. 9 — 16. 



Clytemnestra rostrata Giesbrecht, 1893, p. 566, pi. 45. 



Clytemnestra rostrata Wheeler, 1900, p. 189, fig. 26. 



Clytemnestra rostrata Thompson & Scott, 1903, p 258. 



Clytemnestra rostrata Esterly, 1905, p. 214, fig. 54. 



Clytemnestra rostrata Norman & T. Scott, 1906, p. 140. 



Clytemnestra rostrata Farran, 1908, p. 91. 



Clytemnestra rostrata van Breemen, 1908, p. 180, fig. 194. 



Four males and one female identical vvith the species clescribed by Professor G. S. Brady 

 in the report on the 'Challenger' Copepoda, were obtained from the plankton collected at the 

 following stations. 



Stat. 81, 1 male. -- Stat. 142, 1 male. — Stat. 174, 1 female. — Stat. 213, 1 male. — 

 Stat. 304, 1 male. 



Giesbrecht in his great work distinguishes the female of Clytemnestra rostrata (Brady) 

 from Ciytenniestra scntellata Dana by the proportional length of the joints of the antennules. 

 The second last joint of the antennules of Clytemnestra rostrata is very distinctly shorter than 

 the third last joint. lts length is contained nearly six times in the length of the last joint. 

 The second last joint of the antennules of Ciytenniestra scutellata is slightly longer than the 

 third last joint. lts length is contained twice in the length of the last joint. 



Clytemnestra rostrata appears to have a moderately wide distribution in the great oceans, 

 but some of the records of its occurrence are perhaps doubtful. The species recorded by mv 

 father from the Gulf of Guinea as Clytemnestra rostrata is evidently identical with Dana's 

 species as the illustration of the female antennule is similar to the figure given by Giesbrecht. 



39. Family Pontostratiotidae nov. 



The body is provided with a well defined sharp pointed rostrum. The principal furcal 

 seta is in the form of an extremely long slender setiferous spine, with a jointed distal end 

 carrying a plumose seta. The antennules are six to eight-jointed. The distal end of the upper 

 margin of the first joint is produced into a knob. The exopodite of the antennae is short and 

 one to four-jointed. The mandibles, maxillae and maxillipedes are well developed. The second 

 pair of maxillipedes is not prehensile. The exopodite and endopodite of the four pairs of feet 

 are three-jointed. The fifth pair of feet is elongate and two-jointed. 



The type of this family is Pontostratiotes abyssieola Brady 1883, and it includes the 

 genus Aegisthus Giesbrecht. The very pointed cephalic segment, and the extraordinary development 

 of the principal furcal seta are quite sufficiënt to separate the members of this family from any 

 of the other families belonging to the Harpacticoida. 



