CHALIMU8. 279 



Kroyer seems disposed to consider it merely as the 

 young of a Caligus, but farther observations are necessary 

 to confirm this. The general appearance is that of a 

 Lepeoptheirus ; but we can trace four distinct articulations 

 in the thorax, and three in the abdomen. 



The frontal plates are well developed, and want the 

 small lunules or sucking- discs on the lateral portions ; 

 but instead of these, have arising from the central part of 

 its anterior margin a long and slender organ, rather in- 

 distinctly articulated at its base, and terminated by a 

 round expansion like a sucker, by which it fastens itself 

 to the body to which it is found attached. The presence 

 of this organ would lead us to suppose that this animal 

 must lead a much more sedentary life than the rest of the 

 Caligida3 ; and it would appear in this respect to connect 

 it with some of the Lerneada3, which we shall find to 

 possess a somewhat similar organ of prehension. 



1. CHALIMUS SCOMBRI. Tab. XXXIII, figs. 5, 5 , b. 



CHALIMUS SCOMBRI, Burmeister, Nov. Act. Acad. Nat. Cur. Bonn., 



xvii, 294, t. 23, f. 13. 

 Kroyer, Tidsskrift, ii, t. 1, f. 1. 

 M. Edwards, Hist. Nat. Crust., iii, 457. 



Description. Carapace elongated oval, somewhat nar- 

 rower at the anterior extremity, and then gradually 

 becoming broader posteriorly. Frontal plates large, well- 

 developed, and prominent. Thorax composed of four 

 distinct segments. Abdomen large, and consisting of 

 three joints ; the last terminated by two tolerably-sized 

 caudal plates, each sending off three or four short seta3. 



Hab. Belfast Bay, attached to a Caligus Mutteri, 

 W. Thompson, Esq. 



