30 



•19 



' 14 



■ 10 • 5 • 8 • 5 • 10 



1 ' 



2 ■ 



3 



• 4 • 5 ■ 6 ■ 7 * 8 ' 9 



30 



' 19 ' 



1 10 



■ 14 • 3 • 7 ' 8 • 4 ' 10 



of the Fishery Board for Scotland. 251 



Female 

 Male 



Posterior antennas of moderate length, three-jointed ; joints nearly 

 equal, a small one- (? or two-) jointed secondary branch springs from the 

 end of the first joint, and bears three subequal terminal hairs ; two of these 

 hairs arise from a common and somewhat dilated basal part which may 

 possibly represent a rudimentary second joint, but this is doubtful. 

 Mandibles moderately stout, the biting part broad with several strong 

 tooth-like processes, and a divergent, marginal, setiferous spine ; the palp 

 with two small branches and one or two terminal hairs, Maxillae small ; 

 the terminal part, which is comparatively broad, is furnished with several 

 spiniform teeth on the inner distal margin, and exteriorly with three 

 small marginal setiferous lobes. Anterior foot-jaw small, two-jointed; the 

 first joint with two marginal setiferous lobes, the last joint small and 

 produced into an elongate slender process, bearing at its apex a stout 

 plumose hair, and exteriorly, near the base, a plain slender seta. Posterior 

 foot-jaw strong, and armed with a powerful clawed spine. The first four 

 pairs of . swimming feet have both branches three-jointed and elongate; 

 the first joint of the inner branch of the first pair longer than the entire 

 outer branch, and furnished with an elongate seta on the lower half of 

 the inner margin; the two last joints are short, the second being the 

 shorter of the two. Inner branches of each of the other three pairs 

 shorter than the outer, — especially in those of the fourth pair; all the 

 four pairs furnished with moderately long plumose setae. The inner part 

 of the basal joint of the female fifth pair moderately broad, furnished 

 with four elongate scta3 on its inner margin ; the outer part is laterally 

 produced and attenuated, and forms the base of a single elongate seta, 

 The second joint is long and slender (fig. 12), and furnished with five 

 setre, — three on the outer margin, one on the inner margin near the apex, 

 and an apical seta. The fifth pair in the male are very small ; the basal 

 joint is scarcely produced posteriorly, and bears three subterminal seta? 

 the lateral produced part bears a single hair, the second joint narrow, 

 ciliate on the outer margin, and furnished with one terminal seta, and 

 another on the inner margin, both being of moderate length. The first 

 abdominal segment bears two small setiferous lateral appendages, as 

 shown in fig. 16. Caudal stylets elongate, slender, longer than the last 

 abdominal segment, each with one extremely long and a few short 

 terminal setae. The posterior margins of all the cephalo-thoracic and 

 abdominal segments are more or less distinctly denticulate. 



A variety occurs, somewhat smaller than that described (figs. 17, 18), 

 which has the anterolateral angles of the first body segment rounded instead 

 of angular ; the posterior margins of all the body segments spiniferous 

 instead of denticulate, and also armed at the postero-lateral angles with 

 two strong spines and several small setae. To distinguish this variety I 

 have named it var. spinosa. 



Habitat — Off St Monans, Firth of Forth. Frequent. I first obtained 

 this species two or three years ago, but for want of time to study its 

 structure and affinities, it was laid aside, along with some others, till a more 

 convenient season. With the assistance of my son, I am now able to 

 describe this and several other interesting members of the Forth fauna. 



Paramesochra* no v. gen. (provisional name). 



Body subpyriform ; anterior antenna?, short, seven-jointed in the female ; 



* Near Mesochra, Boeck, which it resembles in several important points, especially 

 in the structure of the first four pairs of swimming feet. 



