52 BRITISH PARASITIC COPEPODA. 



In Charles Branch Wilson's figure of the fourth pair of legs 

 all the three spines with which the end joint is furnished 

 spring from the apex, whereas in our specimen the outer 

 spine springs from a notch on the outer margin a short 

 distance from the apex. 



A young specimen representing the chalimus stage of this 

 Caligus (PI. V, fig. 3) was obtained along with the adult. 

 The siphon is still present showing a dilated, two-jointed 

 base ; the carapace is elongate-ovate in outline, the free 

 thoracic segment is concealed, and the abdomen is very short. 

 The frontal plates also slope backwards at a considerable 

 angle. 



The distribution of Caligus centrodonti, so far as known, 

 appears to be somewhat limited. The only record, other than 

 those for the British Islands, is that of Kroyer. The speci- 

 men recorded by him as Caligus abbreviatus was obtained on 

 a Labrus bergylta at Bergen in 1839. The species is de- 

 scribed in C. B. Wilson's work on ' North American parasitic 

 Copepods/ but the specimens, which were taken in the gill- 

 cavity of Pagellus centrodontus, were sent from England by 

 the Kev. A. M. Norman. 



5. Caligus gurnardi Kroyer. 

 (Plate VIII, figs. 1, 2.) 



1863. Caligus gurnardi Kroyer. (71) ser. 3, vol. ii, p. 150, pi. ii, figs. 

 3 a-g. 



1896. Caligus gurnardi Bassett-Smith. (7) p. 157. 



Female. Carapace equal to about three-fifths of the 

 total length, and rather longer than broad; frontal 

 plates only slightly arcuate, lunulge rather small. 

 Free thoracic segment distinct, small; genital segment 

 obcordate, about half as long as the carapace, its 

 greatest width about equal to the length, posterior 

 margin subtruncated. Abdomen short, uniarticulate, 

 length scarcely equal to twice the width. Caudal 

 rami short. 



Antennules of moderate size, the end joint narrow 

 and about as long as the proximal one. Sternal fork 

 tolerably large with moderately long and somewhat 

 divergent branches. Fourth pair of thoracic legs 

 elongated with the ramus biarticulate. Length 6-7 mm. 



