122 Pari III. — Twenty-first Annual Report 



Genus Enhydrosoma, Boeck (1872). 



Enhydrosoma gracile, T. Scott, sp. n. PI. ii., figs. 16-26; pi. iii., fig. 1. 



Description of the Female. — Body slender, cylindrical, slightly 

 encurved, but otherwise similar to E. curvatum, Brady and Robertson 

 (fig. 16). Length of specimen represented by the drawing about '45 mm. 

 (Jj of an inch). 



Antennules very short, moderately stout, and sparingly setiferous ; they 

 are composed of four joints, the first three being sub-equal in length, but 

 the last is considerably smaller than any of the others (fig. 17). The 

 formula shows approximately the proportional lengths of the various 

 joints : — 



1 • 2 • 3 • 4 



22 • 18 • 19 • 11 



The antennas (fig. 18) appear to be somewhat like those of E. curvatum. 



The mandibles (fig. 19) are also similar to those of the same species. 



The second maxillipeds (fig. 20) have basal joint short, but the pre- 

 ceding one is elongated, and the terminal claw is slender and moderately 

 short. 



The first thoracic feet are somewhat like those of 0. curvatum ; the 

 inner branches are short and two-jointed, the second joint being only 

 slightly longer than the first, and their extremities, which do not reach to 

 the end of the second joint of the outer branches, bear two elongated 

 slender setse feathered at the end ; the outer branches are three-jointed ; 

 the first joint is fully as long as the entire length of the next two, but the 

 end joint is shorter than the second one ; each of the three joints is 

 furnished with a moderately long and very slender seta on its outer aspect, 

 while the end one also carries two elongated terminal setae similar to those 

 on the inner branches (fig. 21). 



The second, third, and fourth pairs (figs. 22 and 23), which appear to 

 differ little from each other, have the inner branches very short and com- 

 posed of two joints, the first being very small, while the end joint is 

 furnished with a few terminal setse as shown by the figures ; the outer 

 branches are three-jointed and of moderate length and stoutness, the 

 middle joint is slightly shorter than the first or third. 



The fifth pair are broadly foliaceous, distinctly two-branched, and both 

 branches are broadly sub-truncate at the end and provided with five mode- 

 rately stout and elongated setae, the lengths of which vary to some extent 

 as shown in the drawings ; a single seta springs from a small lobe near 

 the outer distal angle of the outer branch (fig. 24). 



The furcal branches are very short (fig. 26). 



The ovisac is small and contains very few ova. 



The male appears to differ little from the female except in the structure 

 of the antennules (pi. ii., fig. 1), and also to some extent in the form of 

 the fifth feet. The fifth pair in the male consists of a rectangular plate 

 about half as long as broad, and obscurely divided into two portions ; the 

 inner portion is furnished with two moderately elongated setae on the 

 lower edge, while the outer portion bears three or four setae as shown by 

 the drawing ( pi. i., fig. 25). 



Habitat. — Shore at Musselbnrgh, Firth of Forth ; moderately rare. 



Remarks. — This species occurred with a number of other curious forms 

 in a gathering collected in 1894. Several other new species were obtained 

 in this gathering, but some of these have already been described.* This 



* See Thirteenth Annual Report of the Fishery Board for Scotland, Part III., p. 167, 

 et seq. ; Ann. and Mag. Nat. Hist. (6), vol. xv., pp. 52-53; Ann. Scot, Nat. Hist., 

 January, 1895. 



