172 Part III. — Thirteenth Annual Report 



plumose, springs from the upper middle portion of the inner margin of the 

 second joint ; a fringe of minute hairs extends along the whole of the outer 

 margin of both joints, and the inner margin is also partially fringed with 

 small hairs ; the first joint is nearly two-thirds the length of the second, a 

 spiniform and coarsely plumose seta, rather longer than the joint, springs 

 from its outer distal angle ; a short, slender, setiferous spine springs from 

 the lower half of the outer margin, and a short plumose seta from the 

 inner margin of the second joint; the end joint is less than half the length of 

 the second, and its armature is somewhat similar to that of the same joint in 

 Idya furcata (fig. 19). The second, third and fourth pairs of swimming feet 

 are somewhat similar to those of that species. The fifth pair are also 

 somewhat similar to those of Idya furcata, but the secondary joint is 

 narrower and more elongate, its extremity is subconical and the setee are 

 less crowded together at the apex (fig. 21). Caudal stylets rather longer 

 than broad. 



Habitat. — An old quarry near Granton, into which the sea ebbs and 

 flows. 



Remarks. — The elongate form of the animal, together with the differ- 

 ence in the proportional lengths of the antennules, the long and slender 

 inner branches of the first pair of swimming feet, and the less powerful 

 armature of the outer branches, are characters quite sufficient to distinguish 

 this from Idya furcata, Baird, and Idya longicornis, T. and A. Scott. 



Trematoda. 



Octobothrium merlangi (Kuhn), (PI. IV. figs. 23, 24). 



This curious parasite was obtained on the gills of a specimen of the 

 Whiting (Gadus merlangus) from the Firth of Forth, in March 1891. 

 Several specimens were obtained. It was first described by Kuhn (Memoires 

 du Museum) in 1830, and afterwards by P. J. van Beneden {Bulletin de 

 VAcademie de Belgique (1) xxiii.) in 1856. The same author also refers 

 to it in his Animal Parasites (vol. xx. of the International Scientific 

 series), p. 261 (1876). 



This parasite does not seem to be very common in the Firth of Forth — 

 at anyrate I have only once observed it. 



I am indebted to my kind correspondent, Dr R. Blanchard of Paris, for 

 most of the above information concerning this interesting parasite. 



DESCRIPTION OF THE PLATES. 

 Plate III. 

 Stenhelia refiexa, n. sp. 



Fig. 1. Female — lateral view, . . . x 52 diameters. 



Fig. 2. Autenuule— female, ..... x 380 



Fig. 3. Antenna, ...... x 380 



Fig. 4. Mandible and palp, ..... x 380 



Fig. 5. Posterior foot-jaAv, ..... x 380 



Fig. 6. Foot of first pair of swimming feet, x 253 



Fig. 7. Foot of fourth pair, . . . . x 127 „ 



Fig. 8. Foot of fifth pair, . . . . x 253 „ 



Fig. 9. Last two abdominal segments and caudal stylets, . x 190 



