1881.] Variations in a Copepod Crustacean. 695 
The fifth pair of legs in the male (Fig. 10) are very dissimilar. 
They both arise from a quadrate coxal joint; the left leg consists 
7/ 
Fic. 9.—Fifih pair of legs of the fe- Fic, 10. or tay pair of legs of the 
male. a, inner, and 4, outer branch. male. a, right, and 4, left leg. 
of four joints, the first joint is quadrate and about one-third wider 
than long, slightly enlarging distally. The second joint is some- 
what enlarged distally, about twice as large as the preceding 
joint, and bears a strong, wedge-shaped, blunt and finely serrate 
spine at the inner, and a shorter, slender one at the outer inferior 
angle. The third joint is clavate and distally tapering. The 
fourth joint is composed of an anteriorly notched, narrow basal 
piece exteriorly terminating with an incurved dactyl. The joint 
is from base to tip of dactyl, about two and a half times longer 
than the preceding joint; it terminates interiorly with another 
dactyl, nearly as long as the other; is finely serrate on both 
Sides and acts in closing as a forceps. The right leg consists of 
five joints, the basal and the second joints are quadrate, the latter 
enlarges distally and bears a smaller blunt spine at the inner, and 
a larger one at the outer angle. The third joint is subquadrate, 
slightly tapering distally, the fourth joint is clavate, bearing a 
slender spine at the middle of its outer margin, and the fifth con- 
stitutes a slender incurved dactyl as long as the preceding joint, 
finely rugose on the distal half of its inner margin, and is so 
jointed as to close back against the inner margin of the fourth 
joint, which thus acts as a hand. The left leg (in Fig. 10, 4, pur- 
posely drawn larger) reaches only about to the tip of the third 
joint of the right leg. 
In the family of Calanidz, in general, the abdominal segments 
are considerably narrower in the male than in the female, the for- 
mer consisting of five, the latter of four segments. The first of 
