106 ME. T. SCOTT OX ENTOMOSTEACA 



Genus Clytemnestra, Dana. 



Clytemnestra, Dana, Proc. Amer. Acad. Sci. 1849. 

 Goniojjsyl/us, Brady, Report ' Challenger/ Copepoda, 1883. 

 Goniopelte, Claus, Arb. Zool. Inst. Wien, 1889. 

 Saphir, L. Car. 1890. 



Head and first thoracic segment coalescent. Forehead usually subrostrate. The 

 joints of the cephalothorax much constricted in front, dilated behind so as to form 

 jirominent lateral triangular processes. Anterior antennee 6- to 8-jointed, geniculate in 

 the male. Posterior antennae 3(or 4 ?)-jointed ; secondary branch wanting, or very 

 small and rudimentary. Mandible slender, apex obscurely digitiform ; the palp absent 

 or very rudimentary. Maxillae also rudimentary. Anterior foot-jaw small, clawed at 

 the apex. Posterior foot-jaw elongate, 2- or 3-jointed; terminal claw, in the male, long 

 and powerful, in the female small. First pair of swimming-feet 2-branched, inner 

 branch 3-jointed, the outer with one to three joints. The second, third, and fourth 

 pairs nearly alike, 2-branched, both branches 3-jointcd. Feet of fifth pair 1-branched, 

 the branches similar and 1-jointed, and the same in both sexes. 



Clytemnestra rostrata (Brady). (PL XII. figs. 47-57 ; PI. XIII. figs. 1-3.) 



188.3. Goniopsyllus rostratus, Brady, Report on the ' Challenger ' Copepoda, p. 107, pi. xlii. figs. 9-16. 



1849. Clytemnestra (?) scuteUata, Dana, Proc. Amer. Acad. Science. 



1860. Clytemnestra (?) tenuis, Lubbock, Trans. Linn. Soc. vol. xxiii. p. 180, pi. xxix. figs. 6, 7. 



1889. (?) Goniopelte gracilis, CLaus, ArlD. Zool. Inst. Wien, t. ix. 



Length about 1-25 mm. The body is usually more or less curved inwards. The fore- 

 head is subtruncate, with middle part produced forward so as to form a prominent rostrum. 

 Postero-lateral angles of the tirst four thoracic segments extended backward into 

 angular jirocesses ; the last thoracic segment smaller than either the preceding one or 

 the first al)dominal segment, its postero-lateral angles not produced. Abdomen 5-jointed 

 in the male, 4-jointed in the female ; the first abdominal segment in the female composed 

 of two coalescent segments, with usually a pellucid spot in the median dorsal line 

 (PI. XII. fig. 48). Body, seen dorsally, elongate, narrow, and tapering gradually from 

 the head backwards. Caudal stylets short, about as long as the last abdominal segment, 

 each furnished with a few short marginal hairs, and in the male with two long plumose 

 terminal setse. The plumose setae are wanting in the female and are replaced by two or 

 three plain and very small hairs. Anterior antennae in both male and female 7-jointed, 

 the proportional lengtlis of the segments being nearly as follows : — 



Male. 12 . 19 . 6 . 22 . 3 . 18 . 25 

 1 2 3 4 5 6 7 



Female. 12 . 20 . KJ . 15 . 15 . 17 



The anterior antennae of both male and female are sparingly setiferous. There is a 

 hair-like filament on the upper margin and near the middle of the third joint in both 

 sexes, while the upper distal angle of the fourth segment and the extremity of the last 



