148 BRITISH COPEPODA. 
ciliated ; the external ovate joint is fringed with cilia, 
and bears also five ciliated apical setz of unequal 
length ; in the male (fig. 14) the basal joint is obsolete, 
and the outer plate, though more angular, is very 
similar to that of the female. The second and third 
abdominal rings (fig. 15) are denticulated along the 
hinder border and at the angles. Caudal segments 
very short and broad. Inner tail seta about twice as 
long as the outer, and finely aculeate beyond the 
middle. Length z'gth of an inch (‘98 mm.). : 
This fine species 1s of common occurrence in the 
littoral and laminarian zones, and is likewise frequently 
taken by the dredge, and by the towing-net in the open 
sea. Different examples vary very much in amount of 
setiferous and spinous armature (especially in the fifth 
pair of feet) as well as in slenderness or robustness of 
build, and it seems to me that it is on mere degrees 
of variation in these respects that the species gracilis, 
Claus, and elongatus, Boeck, have been founded. I have 
often met with examples which might have been referred 
to one or other of these species, but have been unable to 
find any permanent and trustworthy diagnostic mark 
separating them from the typical H. chelifer. I there- 
fore prefer to consider the two as varieties only. The 
foot, represented in Plate LXV, fig. 10, and the foot- 
jaw in fig. 8, are, I believe, well-marked examples of 
those organs in the gracilis form, specimens of which 
from the Mediterranean Professor Claus has been 
good enough to send me. Itis, however, only right 
to add that Dr. Claus has examined the subject with 
great care, comparing specimens from widely separated 
