FROM THE GULF OF GriNEA. 47 



Genus Scolecithrix, Brady. 



ScolecithrLv, Brady, Report 'Challenger' Copepoda (1883). 



Scolecithrix securifrons, n. sp. (PI. IV. figs. 40-56; PL V. fig. 1.) 



Length, exclusive of tail-setae, about 4 mm. Cepbalothorax robust, the anterior 



segment fully two-tbirds the length of the body. Forehead with a prominent median 



keel, which is continued do\Aniwards to the slightly furcate rostrum. Anterior antennse 



longer than the body, 23-jointed in the female, 19-jointcd in the male. The annexed 



formula shows very nearly the proportional lengths of the joints : — 



Male. 10 ■ 11 . 5 ■ 6 . 6 . 7 ■ 6 . 41 . 22 . 1.3 . 13 ■ 14 . 13 . 10 . 9 . 13 . 13 . 12 . 3 ' 



12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23. 

 Female. 13 . 12 . 6 . 6 . 7 . 7 . 7 . 21 . 9 . 11 . 14 . 15 . 15 . 15 . 14 . 14 . 14 . 13 . 13 . 13 . 14 . 12 3. 



The long eighth joint has one or two pseudo-divisions, indicating the possible 

 coalescence of two, if not three, smaller joints. The secondary branch of the posterior 

 antennse is half as long again as the primary one, 5-jointed, the third and fourth 

 joints small, the last joint with three terminal setre ; several setse spring from the vicinity 

 of the two small joints ; the primary branch is furnished with a number of terminal 

 setae, which, with the others, are all more or less plumose. Mandible-palp with two 

 small branches set wide apart, and each with numerous plumose hairs. Maxillae and 

 other mouth-organs as in Scolecithrix Dance. Pirst pair of swimming-feet small, inner 

 branch 1-jointed, with a lobe-like appendage, terminal spine of the outer branch small. 

 All the joints of the second and third pairs are armed with transverse curved rows of 

 short stout spinules, and the terminal sabre-like spines of the outer branches have their 

 exterior margin strongly and coarsely toothed. The fourth pair Avants the transverse 

 rows of spinules, but is otherwise similar to the second and third pairs. The fifth jjaii' 

 in the female is very small, 1-branched, 2-jointed, and with a moderately long 

 slender, curved, terminal spine, the distal half serrate on the outer margin ; a small 

 blunt process springs from the inner distal angle of the terminal joint, close to the base 

 of the elongate spine ; this spine was apparently hinged to the extremity of the last 

 joint, for in one or two specimens it was turned upAvard at a right angle to the joint, and 

 in such a manner as to allow of its being ap]jlied to the base of the first abdominal 

 segment. The fifth feet in the male are strongly developed ; the left foot is 1-branched, 

 3-jointed, with a curved finger-like process at the extremity ; the right has a slender 

 1-jointed inner branch, curved outwards so as to be opposed to the 2-jointed clawed 

 terminal part of the outer branch ; the basal part to which the two branches are attached 

 is much dilated. Abdomen in the female short, first segment larger and much wider 

 jwsteriorly than the next; the posterior margiii of the abdominal segments in both sexes 

 fringed with hairs. Caudal stylets short, divergent, each with four long terminal 

 plumose setae nearly equal in length, and a small hair near the base of the inner seta. 



Habitat. Station 2, 50 fathoms tow-netting, January 1st (niglit collection). Lat. 7°33'N., 

 long. 15° 18' W., 25 fathoms tow-netting, January 2nd (night collection). Lat. 1° 55' 5" N., 

 long. 55° 55' 5" E., 360 fathoms tow-netting, January 22nd (day collection). Lat. 0° 25' 1" N., 



