Parasitic Gopepoda of Fish. 11 



found fixed on to animals of different families, as Ghondra- 

 canthus and Aiichorella ; or even sometimes in great numbers 

 I have taken them fixed on to the gill-rakers of the cod and 

 gurnard and the fins of the sea-trout. In other cases one may 

 find as many as six in various stages of development attached 

 to the adult forms. At first the carapace is very narrow, with 

 its apex at the place of attachment of the frontal filament, the 

 thoracic portion being proportionately large, having the double 

 eye near the centre. The anterior antennse are quite free 

 from the frontal lobes. The maxillipeds increase in size as 

 the carapace broadens, and before becoming detached the 

 animal closely resembles the form of the adult ; but I have 

 not yet found any with lunulge on the frontal lobes, even in 

 those taken associated with species of Galigus. 



During the course of my observations the following new or 

 noteworthy species have been obtained * : — 



Caligus scomheri, sp. n. (PI. III. fig. 2.) 



I have been unable to place this with any recorded species, 

 and have therefore named it after the fish it is taken from. 

 It is found on the inner surface of the operculum of Scomber 

 scomber. It much resembles Galigus diaphanus (Nordmann 

 and Kroyer, not Baird) ; but the carapace is oval, instead of 

 being rounded, and the abdomen is much longer. 



Carapace oval, narrow in front ; posterior antennse with 

 well-marked palp ; second pair of maxillipeds small; furcula 

 small, with simple elongated branches, hardly spreading; 

 caudal plate large, with three long plumose setae, and one 

 smaller one placed rather far outside. 



Caligus brevipedis^ sp. n. (PI. III. fig. 1.) 



Two specimens of this curious form were taken in August 

 from the gill-cavity of Motella tricirrata. It differs from all 

 other described species in the rudimentary condition of the 

 fourth pair of thoracic limbs. The same character was found 

 in both specimens, therefore it could not be an abnormality. 



Carapace small, as broad as long, but rather narrower 

 anteriorly. Frontal plates well developed ; lunulte of moderate 

 size ; anterior border of basal joint of anterior antennaj fringed 

 with fine hairs; second joint terminating in about ten small 

 bristles. Posterior antennae strongly hooked, palp on basal 

 joint blunt ; hamulus subsidiarius anterior acutely bent ; 



* For a complete list of the parasitic Copepoda found ou fish at Ply- 

 moutk see Jouru. Marine Biol. Assoc, vol. iv. no. 2. 



