neio and rare Crustacea from Scotland. 143 



The secondary branches of the posterior antennae are composed 

 of two moderately long joints ; the first joint is provided with 

 a plumose seta at the distal end and the second with two 

 marginal setas near the base and three at the apex ; all the 

 setse are plumose. Posterior foot-jaws stout, the last joint 

 somewhat ovate, its greatest breadth being equal to fully 

 half the length ; it is furnished witli a comparatively long 

 slender seta near the middle of the inner margin, and the 

 terminal claw reaches to beyond the proximal end of the joint 

 to which it is attached. The first pair of swimming-feet 

 have the inner branches slender and considerably longer than 

 the outer ones ; the outer branches are only about two thirds 

 the length of the inner; the inner terminal claw of both 

 branches is very slender and elongate, and, like the others, 

 only slightly curved at the extremity. The second, third, and 

 fourth pairs are somewhat like those of Thalestris forficula^ 

 Claus, but the proportional lengths of the joints are slightly 

 different ; in the fourth pair the last joint of the inner branches 

 is only equal to three fourths of the combined lengths of the 

 first and second joints ; the inner branches of the third pair 

 in the male are armed with a spiniform and slightly hooked 

 claw-like terminal appendage (fig. 7). The basal joints of 

 the fifth pair are broadly triangular and the apex reaches to 

 near the middle of the secondary joints ; the inner and outer 

 margins are fringed with small close-set hairs, the basal joints 

 are also each furnished with five plumose setse of unequal 

 length arranged round the distal end — one at the apex, one 

 on the outer margin, and three on the inner margin ; the apical 

 seta is considerably longer than any of the others; the outer 

 secondary joints are subcyliudrical, fringed with small close- 

 set hairs on both margins, and furnished with eight setaj — 

 three on the distal half of both the outer and the inner mar- 

 gins, and two at the apex ; the inner apical seta and the one 

 on the inner margin next to it are much longer than any of 

 the others ; there are only two small spiniform apical setaj on 

 the basal joint of the fifth pair in the male. Abdomen and 

 caudal stylets nearly as in Thalestris for jicula. 



Hab. Among mud near low-water mark at Seafield, in the 

 vicinity of Leith, Firth of Forth. 



Remarks. This species somewhat resembles Thalestris 

 forficala, Claus, but differs in the following among other 

 particulars : — The anterior antennee (the antennules) are nine- 

 jointed, and the sixth and last joints are each of them equal to 

 the combined lengtlis of the seventh and eighth and of greater 

 length than either of the fourth or fifth. The inner branches 

 of the first pair of swimming-feet are very long and slender, 



