4 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
Many immature stages including the last copepodid stage were 
collected from the sharks off South America. When some of these 
copepodids were cleared in KOH and lactic acid, the first chalimus 
stage could be seen within. By carefully splitting open the copepodid, I 
teased out the developing chalimus. These chalimus stages were identi- 
cal to first chalimus stages collected free in the gill chamber of the 
shark. Two successive chalimus stages also were found. These im- 
mature stages are described below. For a description of the adults of 
this species, see Cressey (1967a). 
Last copEPopID.—Body form as in figure 1. Total length 6.77 mm 
(6.23-7.43) based on an average of 240 specimens, greatest width 
4.07 mm (3.78—4.38) based on an average of 20 specimens (all measured 
specimens taken from a single shark at R. V. Anton Bruun Station 554). 
Dorsal surface unornamented. Two “eye spots” with more heavily 
pigmented area surrounding and between them in anterior third of 
cephalon. Posterior corners of first free thoracic segment produced, 
extending nearly to end of second free thoracic segment. Genital 
segment slightly longer than wide (1.3 x 1.1 mm in one specimen). 
Abdomen 1-segmented, somewhat triangular, wider than long (.3 x .4 
mm in one specimen). Caudal ramus (fig. 2) 536u wide, 590 long at 
outer edge, 295u long at inner edge (based on one specimen) ; armed 
with six plumose setae, four long terminal and two short subterminal. 
Adhesion pad present on ventral surface immediately posterior to 
first antenna. 
First antenna (fig. 3) 2-segmented: basal segment with several 
short plumose spines, proximal two more heavily spinose; terminal 
segment with seven setae, posterior four plumose. Second antenna 
(fig. 4) with terminal segment in form of a claw, tip of claw twisted. 
Mouth tube and mandible of usual caligoid form, mandible with 10 
teeth. First maxilla (fig. 5) a small lobe with three short setae and 
posterior projection bearing process with rugose tip. Second maxilla 
(fig. 6) with two terminal claws and subterminal hirsute process, 
claws ornamented as in figure 7. Maxilliped (fig. 8) stout, bearing 
bladelike claw opposed by striated area on basal segment. 
Legs 1-4 (figs. 9-12) biramose. Rami of legs 1-3 2-segmented. 
Exopod of leg 4 1-segmented, endopod 2-segmented (see spine and 
seta formula below). Leg 5 (fig. 13) a knob bearing two setae, one 
naked and one plumose, on lateral margin of genital segment. Leg 6 
absent. 
Color in life: dark mahogany brown. 
CHALIMUS I, MALE.—Body form as in figure 14. Total length 6.6 
mm, greatest width 3.1 mm (all measurements based on a single 
specimen taken from the same shark as copepodids). 
