of the Fishery Board for Scotland. 123 



Enhydrosoma is a smaller and more slender form than E. curvatum ; the 

 female antennules are apparently only four- instead of five- jointed, 

 the third and fourth joints in E. curvatum being in this species completely 

 coalescent. The first pair of thoracic feet are also somewhat different in 

 the two species, but a greater difference is observed in the structure of 

 the female fifth pair ; in E. curvatum there is a distinct though small 

 secondary branch, but in the present species the branches, which are 

 sub-equal, do not appear to be distinctly separated. 



Enhydrosoma minutum, T. Scott, sp. nov. PI. iii.,fig. 25 ; pi. vi., figs. 1-5. 



Description of the Female. — This is a small but moderately stout 

 species as shown by the drawing (fig. 1, pi. vi.). Its entire length, 

 exclusive of antennules and tail setse, scarcely reaches to '4 m.m. (about 

 ^ of an inch). 



The antennules (fig. 2, pi. vi.) are composed of five joints, but the 

 fourth is very small ; the armature consists of a number of moderately 

 stout setse, a few of them being plumose, and the end joint carries a stout 

 terminal spine as shown by the figure. 



The mouth organs resemble generally those of E. gracile, but the 

 second maxillipeds are comparatively rather stouter (fig. 3, pi. vi.). 



The first pair of thoracic feet, which appeared to be somewhat similar 

 in structure to the first pair in E. gracile, were accidentally damaged, so 

 that a correct drawing of them could not be prepared. 



The second, third, and fourth pairs are all somewhat alike in structure 

 (pi. iii., fig. 25 ; pi. vi., fig. 4), and their outer branches do not differ 

 greatly from the outer branches of the feet similar to them in E. curvatum, 

 but the inner branches are very small, they each consist of two joints, the 

 first joint being much shorter than the other, while the end joint tapers 

 towards the distal end, and carries a single elongated terminal seta. 



The fifth pair (fig. 5, pi. vi.) are broadly foliaceous and resemble those 

 of E. gracile ; but the secondary branches are more distinctly articulated 

 to the basal joints, and the setae of the two joints appear to be stouter. 



The f ureal joints are extremely short. The female appears to carry one 

 ovisac with several moderately large ova, 



Habitat. — Aberdeen Bay, Station V., Nov. 12, 1901. One specimen 

 only. 



Remarks. -Enhydrosoma minutum differs from the species already 

 described by the difference in the structure of the antennules, and by the 

 form and armature of the inner branches of the second, third, and fourth 

 pairs of feet. No male specimen has been observed. 



Enhydrosoma curvatum (Brady and Robertson). 



1875. Rhizothrix curvata, B. and R., Brit. Assoc. Rept., p. 197. 



1880. Enhydrosoma curvatum, Brady, Mon. Brit. Copepoda, vol. 



ii., p. 98, pi. lxxxi., figs. 12-15; pi. lxxxii., figs. 11-19. 



This also occurred in the gathering from the old quarry near Granton ; 

 it is quite distinct from the two species, E. gracile and E. minutum, 

 just described ; the difference in the structure of the fifth thoracic feet 

 would alone be sufficient to separate them ; it is, moreover, a somewhat 

 larger species. There is a previous record of this species from the Forth 

 district, but from a different part of the estuary,* as well as from other 

 places around the Scottish coasts. 



* Eighth Annual Report of the Fishery Board for Scotland, Part III., p. 319 (1890). 



