54 BRITISH PARASITIC COPEPODA. 



divergent branches, which have their ends obliquely 

 truncated. Fourth pair of thoracic legs small, basal 

 joint tolerably stout ; ramus short, two-jointed, and 

 armed with sabre-like spines, the first joint with one 

 on the outer distal angle, and the second with two at 

 the apex, the spines moderately elongated, those at 

 the apex being longer than the joint from which they 

 spring, also with a minute tooth on the inner distal 

 angle. The fifth pair consisting each of a minute 

 setiferous plate on the postero-lateral angle of the 

 genital segment. Egg-strings short, containing a 

 comparatively small number of tolerably large ova. 

 Length about 3*5 mm. 



Male. The male is smaller than the female, being 

 only about 2'6 mm. in total length. It does not differ 

 greatly from the female except that, as usual, the 

 second maxillipeds are larger and the genital segment 

 is much smaller. Colour reddish-brown, broken up 

 into minute patches of a lighter and darker coloration. 



Habitat. Parasitic on the gills of a striped wrasse, 

 Labrus mixtus L., captured in the Firth of Clyde in 

 January 1900, and sent to the Laboratory of the 

 Fishery Board for Scotland at Aberdeen by Mr. 

 Robert Duthie, the Fishery Officer at Grirvan. Also 

 found on the gills of Labrus mixtus and Laln-nx u/acu- 

 latus captured in the Irish Sea (A. Scott). 



7. Caligus zei Norman and T. Scott. 

 (Plate VII, fig. 1 ; Plate VIII, figs. 3-9.) 



1906. Caligus zei Norman & T. Scott. (88) p. 206, pi. xxii, figs. 1-8. 



1907. Caligus zei A. Scott. (Ill) p. 93, pi. i. 



Female. Carapace suborbicular, length and breadth 

 nearly equal, margins only slightly arcuate. Frontal 

 plates and lunulse of moderate size. Free thoracic 

 segment about as long as broad, rather small. Genital 

 segment subquadrate and equal to about a third of 

 the entire length of the animal; length and width 

 nearly equal, and the postero-lateral angles, which are 



