206 BRITISH PARASITIC COPEPODA. 



Antennules small, apparently four-jointed, but the 

 articulation between the first two joints indistinct. 

 Antennae and mouth-organs somewhat similar to those 

 of BracMella thy mil. The second maxillipeds spring- 

 ing from the lower half of the cephalo thorax and 

 reaching to about the proximal end of it ; free except 

 at the tip, where they are jointed to a horn-coloured 

 chitinous plug. Length from the extremity of the 

 cephalothorax to the end of the genital segment 

 about 15 mm., and 17 mm. to the tip of the posterior 

 appendages. 



Male. The male is nearly twice as long as broad 

 and measures about 2 mm. in length; it is compara- 

 tively robust, the cephalothoracic appendages are 

 somewhat crowded together at the proximal end, and 

 there is no distinct division between the cephalothorax 

 and abdomen. The antennae (both pairs), mandibles, 

 and maxillae are nearly as in the female ; but both 

 pairs of maxillipeds, though short, are furnished with 

 strong terminal claws. Abdominal appendages very 

 small. 



Habitat. Parasitic on the gills of halibut (Hippo- 

 glossus vulgaris). On large halibut captured in the 

 North Sea, and landed at the Fish-Market, Aberdeen. 



Kroyer records two forms, apparently distinct, under B. 

 rostrata, one from the Hippoglossus here mentioned and the 

 other a shorter form from Hippoglossus pinguis. This 

 form we have not seen. 



3. Brachiella insidiosa Heller. 



(Plate XLVIII, fig. 18; Plate LXII, fig. 2; Plate 

 LXIII, figs. 9-16.) 



1865. Brachiella insidiosa Heller. (58) p. 239, pi. xxiv, fig. 1. 

 1896. Brachiella insidiosa Bassett-Smith. (6) vol. xviii, p. 14, pi. vi, 

 fig. 2. 



1900. Brachiella insidiosa T. Scott, (112) p. 175, pi. viii, figs. 40, 41. 

 1906. Brachiella insidiosa Brian. (21) p. 104, pi. viii, figs. 1 and 4. 



Female. Body tolerably robust. Cephalothorax 

 short, flexuose, and vermiform. Genital segment 



