THALESTRIS. toe 
seta towards the middle of the inner border; in the 
male the outer branch is much longer than the inner 
(fig. 13), bearing three stout spines and two sete, 
while the inner portion of the basal joint has only two 
spines, one of which is very small. Caudal segments 
as long as the last abdominal ring; inner sete longer 
than the abdomen, outer scarcely half that length. 
The whole integument of the animal has a corrugated 
or waved appearance, this being especially conspicuous 
in the fifth pair of feet of the female. Length ;;th 
of an inch (1°8 mm.). 
A very fine and well-marked species, apparently 
local in its distribution, but sometimes occurring in 
moderate abundance. JI have specimens from the 
undermentioned localities :—Westport Bay, Ireland, 
taken in dredge and tow-net, but rare; also in Round- 
stone and Clifden Bays; Scilly Islands, dredged in ten 
to twelve fathoms, and taken im the surface-net and 
amongst weeds at low water; dredged in a depth of 
five fathoms at Oban, and found also on the fronds of 
Laminaria at Tobermory (Rev. A. M. Norman). 
2. THALESTRIS HELGOLANDICA, Claus. Pl. LXI, figs. 
9—14, 
Thalestris helgolandica, Claus. Die frei lebenden Copepoden, 
p. 131, t. xvii, figs. 12—21 (1863). 
Body robust; abdomen short; rostrum broad and of 
moderate length. Anterior antenna (fig. 9) elongated, 
