HATSCHEKIA CORNIGERA. 119 



outer and inner rami also two-jointed and provided 

 with a few apical spines. Caudal rami inconspicuous 

 or obsolete. Length about 2*5 mm. Egg-strings 

 scarcely as long as the genital segment. Colour 

 similar to that of the gills of the fish. 



No males have been observed. 



Habitat. — Parasitic on the gills of sea bream, 

 Pagellus centrodontns De la Roche, captured in the 

 North Sea and landed at the Fish-Market at Aberdeen 

 during the early months of 1908 (T. Scott). 



This species is very slender in proportion to its length, and 

 in this respect it has a resemblance to Kvoyeria ; the head is 

 also proportionally very small. When in situ on the gills of 

 ohe fish, the parasite is not very conspicuous and may be 

 easily overlooked. The horn-like process on the dorsal aspect 

 of the cephalon, best seen in lateral view, is perhaps one of 

 the more distinctive features of the species. 



6. Hatschekia pygmaea T. Scott. 

 (Plate XXXV, figs. 3-7 ; Plate XXXVI, figs. 6-9.) 



1907. Clavella labracis (?) P. J. van Beneden, A. Scott. (Ill) p. 95, pi. iv. 



Female. — Antennules comparatively short, stout, 

 and composed of five articulations, the first being 

 robust and equal to about two-fifths of the entire 

 length of the antennule, the next about half the size 

 of the first, but the remaining three considerably 

 smaller and subeqnal ; the first and second joints 

 furnished with a number of short spatulate hairs on 

 their upper aspect ; the first joint also with a short 

 and stout spiniform seta on the lower distal angle, a 

 minute seta springing from the lower margin of the 

 third joint, while the end one has several similar setae 

 on its lower margin and apex and two small hooks on 

 the upper distal angle as shown in the drawing 

 (PI. XXXV, fig. -4). Antennae tolerably elongated 

 and slender, and terminating in strongly-curved apical 

 hooks. Mandibles and maxillae rudimentary, the 

 former having apparently no serrated apex. Both 

 pairs of thoracic legs biramose, small and more or less 



