are cönsiderably produced and extend beyond the end of the furcal joints. The other abdominal 

 segments are entirelv covered by the genital segment. The furcal joints are moderately long 

 and cylindrical. The joints are nearly three times longer than broad and are furnished with 

 an outer marginal seta (Plate LXV, fig. i). 



The antennules are short and are composed of five joints. The last joint is small. The 

 whole of the distal margin of the first joint and the lower half of the distal margin of the 

 second joint is fringed with short hairs. The third and fourth joints each bear one long 

 sensory filament. 



The antennae, mandibles, maxillae and second pair of maxillipedes are similar to those 

 of Pcltidium pitrpitretim. The* first pair of maxillipedes is similar to that of Eupeltidium glabrum . 



The exopodite of the first pair ot feet is moderately long and slender. It is three- 

 jointed. The second joint is distinctly longer than the first joint. The third joint is very short. 

 It bears one stout and one slender curved claw. The endopodite is narrow and two-jointed. 

 The second joint is furnished with one subapical and two apical setae (Plate LXV, fig. 4). 



The second, third and fourth pairs of feet are similar to those of Pcltidium purpureum. 



The fifth pair is composed of a single highly chitinised and somewhat spiniform joint. 

 The outer margin is furnished with three short setae. The inner margin is furnished with two 

 setae at the base, and one at the middle. The apex is furnished with a short curved claw 

 (Plate LXV, fig. 5). 



Male unknown. 



Occurrence. — One specimen was obtained from the surface plankton collected at 

 Station 142, when the 'Siboga' was at anchor at Laiwui, on the coast of Obi Major. This species 

 is named in compliment to my colleague Mr. James Johnstone, B.Sc. His investigations and 

 reports on the endoparasites of fishes have done much to revive the study and add to the 

 knowledge of the British forms. 



28. Family Porcellidiiae. 

 Genus Porcellidium Claus, 1860. 



The members of this genus are readily recognised by the very depressed body, and by 

 the large flattened triangular first joint of the endopodite of the first pair of feet. The second 

 joint is very short. It is furnished with two moderately strong claws that are densely fimbriate 

 on one side. 



One species belonging to this genus was represented in the material collected by the 

 'Siboga' in the Malay Archipelago. 



1. Porcellidium brevicaudatum Thompson & Scott. 



Porcellidium brevicaudatum Thompson & Scott, 1903, p. 275, pi. XII, figs. 11 — 14. 

 A single female belonging to this species was found in the washings from dredged 

 invertebrata collected at Station 273, at a depth of 13 metres. 



213 



