CHALTMUS. 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 

 Caligidae ; and it would appear in this respect to connect 

 it with some of the Lerneadas, 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. Boun., 

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



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



— 31. 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 tw^o tolerably-sized 

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



Hab. — Belfast Bay, attached to a Caligus Mulleri, 

 W. Thompson, Esq. 



