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 

 denned lucid space of a somewhat semi-circular outline (fig. 1, PI. 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, PI. VIII.). 



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, pi. lxxvii. 



figs. 18-20. 

 1892. Nannopus palustris, Canu (11), p. 166, pi. 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. Nannopus 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 antennae eight-jointed, short. Posterior antennae 

 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. 



* Aewros, slender ; and tyvWos, a flea. 



S 



