118 BRITISH PARASITIC COPEPODA. 



Habitat. Parasitic on the gills of Jago's goldsinny, 

 Ctenolabms rupestris Linn., East Loch Tarbert (a 

 branch of Loch Fyne) (T. Scott). 



The male has not yet been observed. 



The more obvious characters by which this species may be 

 distinguished from H. labracis appear to be its larger size, the 

 different form of the cephalon and genital segment, and the 

 structure and armature of the antennules. 



5. Hatschekia cornigera T. Scott. 

 (Plate XXXV, figs. 1, 2 ; Plate XXXVI, figs. 1-5.) 



1909. Hatschekia cornigera T. Scott. (118) p. 74, pi. iii, figs. 1-7. 



Female. Body narrow and greatly elongated. Head 

 proportionally very small and expanding laterally into 

 broadly-rounded lobes, also produced backward, on 

 the median dorsal aspect, into a blunt-pointed spur- 

 like process ; this segment being distinctly limited, 

 by a constriction, from the thorax, which is narrow 

 where it joins the head. 



No distinct separation between the thorax and the 

 genital segment, the one merging gradually into the 

 other. Genital segment very long and narrow, and of 

 about the same width throughout the width being 

 only equal to about one - sixth of the length ; the 

 segment near its posterior end tapering to the narrow 

 and obscurely bilobed extremity ; abdomen very small 

 and not clearly defined. 



Antennules short, moderately stout, and composed 

 of five articulations which are sparingly setiferous. 

 Antenna? large and armed with strong and hook-like 

 terminal claws. Mandibles and maxilla? somewhat 

 similar to those of H. cluthae. Maxillipeds tolerably 

 elongated and slender, with a short spine arising from 

 the inner aspect and near the proximal end of the 

 second joint, the end joint terminating in a pair of not 

 very strong and slightly-curved spines. Both pairs 

 of thoracic legs biramose; the basiopodite consider- 

 ably enlarged and composed of two articulations ; the 



