of the Fishery Board for Scotland. 253 
The seta on the outside is plain, the others are plumose. Secondary joints 
small, sub-cylindrical, scarcely extending beyond the end of the basal 
joints. Bordering upon the concave exterior margin of the basal joints, 
and near the proximal end of the secondary joints, there is a clearly 
defined lucid space of a somewhat semi-circular outline (fig. 1, Pl. V.). 
Caudal stylets very short, the breadth about equal to the lengths. The 
stylets, being comparatively narrow, are widely apart; and as the last 
abdominal segment, as seen from the side, ends abruptly, the stylets, though 
short, are quite prominent (see figs. 27 and 34, Pl. VIIL.). 
Habitat.—Off Musselburgh and off Aberdour. Frequent. 
Remarks.—This is a well-marked species. When mixed up with other 
forms it is readily distinguished by the abrupt junction of the stylets to 
the last abdominal segment. Though moderately frequent, both in 
material dredged off Musselburgh and Aberdour, no males have yet 
been obtained. 
Genus Nannopus, Brady (1880). 
Nannopus palustris, Brady. 
1880. Nannopus palustris, Brady (8), vol. ii. p. 101, pl. lxxvii. 
figs. 18-20. | 
1892. Nannopus palustris, Canu (11), p. 166, pl. iv. figs. 6-21. 
Habitat.—In pools near the mouth of Cocklemill Burn—a small 
stream that enters the Forth at the east end of Largo Bay. The mouth 
of this stream is comparatively narrow, but immediately beyond:the outlet 
there is a large expanse of low-lying ground intersected by numerous 
furrows or ditches branching off from the main channel of the stream ; 
a considerable portion of this low-lying ground is covered by the sea at 
high-water, and especially during spring tides. This tidal lagoon, as 
it may be called, appears to harbour a peculiar and interesting micro- 
fauna, which has not hitherto been very carefully worked up. Some 
material was collected here by hand-net in August 1890, but it was not 
till a few months ago that there was sufficient leisure to attend to it. 
It was then ascertained that this curious species was not unfrequent in the 
material. MNannopus palustris was discovered by Dr Brady, also, in 
brackish-water pools, at Seaton Sluice, Northumberland, where only a 
few specimens were obtained. Dr Eugene Canu records this species 
also from Wimereaux, France, where it also occurs in somewhat similar 
conditions to those described above. The rudimentary structure of the 
inner branches of the third and fourth pairs of feet appear to be 
characteristic of the species. 
Genus Leptopsyllus,* nov. gen. 
Body elongate, cylindrical, somewhat similar in form to Cylindropsyllus, 
Brady. Anterior antennz eight-jointed, short. Posterior antennz 
three-jointed ; secondary branch small, one-jointed. Mandibles_ well- 
developed, the broad biting part armed with several strong teeth. Palp 
comparatively large, consisting of a moderately stout basal joint, and a 
single two-jointed branch. Other mouth appendages nearly as in Cletodes, 
except that the posterior foot-jaws are three-jointed. Both branches of 
the first pair of swimming-feet short and two-jointed. In the second and 
third pairs the inner branches are obsolete or entirely absent, but the 
outer branches are three-jointed. Inner branches of the fourth pair two- 
jointed ; outer branches three-jointed. Fifth pair foliaceous, small, two- 
branched. 
* Aertos, slender ; and WvaAdos, a flea, 
