new and rare Crustacea from Scotland. 459 
Canthocamptus palustris, var. elongatus, var. n. 
(Pl. XVI. figs. 7-17.) 
Description of the Vartety.—Female. Length ‘7 millim. 
(3 of an inch). Body elongate and slender. Antennules 
eiglit-jointed; the second, fourth, and last joints are subequal 
and Jonger than the other joints, but the seventh joint is 
considerably shorter than any of the others; the formula 
shows the proportional lengths of the joints very nearly— 
_ Proportional lengths of the joints.. 9.12.7.11.7.8.5.10 
Numibenvof the joints... 2. ie Ie 3 Are Gh ie oe 
Antenne moderately stout, three-jointed ; the first joint is 
short, the second and third are longer and nearly equal in 
length; secondary branch small, one-jointed (tig. 9). Man- 
dibles slender and provided with a small two-jointed palp 
(fig. 10). Posterior foot-jaws moderately stout; a small 
seta springs from the inner distal angle of the first joint, and 
another from the margin of the second joint near the distal 
end; terminal claw about equal in length to the second joint 
(fig. 11). Both branches of the first pair of swimming-feet 
are short and of nearly equal length, and are both three- 
jointed ; the inner, which is slightly the longer branch, has 
the second and third joints short and subequal, their combined 
length being only a little more than two thirds of the length 
of the first joint, which is also considerably stouter; the joints 
of the outer branch are inoderately stout and gradually increase 
in length from the basal joint (fig. 12). The second, third, 
and fourth pairs are more elongate than the first, and the 
inner branches are all three-jointed and considerably shorter 
than the outer branches ; the first joint of the inner branches 
is also much shorter than the second and third joints (fig. 13). 
Fifth pair broadly foliaceous ; the produced inner portion of 
the basal joint is shorter than the secondary joint and broadly 
rounded at the end, where it carries five slender sete, having 
a somewhat pectinate arrangement; the two outermost sete 
are much longer than the others and plumose; the secondary 
joint is subrotundate, but somewhat longer than: broad, and 
furnished with five long slender hairs (fig. 14). Caudal 
stylets very short (fig. 17). The abdomen is only sparingly 
hirsute, and the ovisac is large. 
Male. 'Vhe male resembles the female very closely except 
in the antennules and fifth pair of feet; the antennules are 
elongate, nine-jointed, and strongly hinged. In the fifth pair 
of thoracic feet the inner portion of the basal joint is scarcely 
produced and broadly rounded, and bears three terminal and 
