278 



SIPHONOSTOMA ; CALIGUS. 



horny claws directed backwards. The feet-jaws (f, g, h\ to the 



number of three pairs, 

 are instruments of pre- 

 hension, by which the 

 animal attaches itself ; 

 and behind the last pair 

 of these, there is a fork- 

 ed appendage on the 

 central line (*"), which 

 probably assists in the 

 same object. There 

 are four pairs of tho- 

 racic legs ; of which 

 the first three (j, k, l\ 

 formed for swimming, 

 are situated beneath 

 the carapace ; whilst 

 the last (m), which 

 comes forth behind it, 

 is rather adapted for 



FIG. BIOUNDER SIDE OF CALiGus. walking. The abdomen 

 forms but a single seg- 

 ment (p} ; and is furnished with a pair of small fin-like append- 

 ages (q). One of the most curious parts in the structure of this 

 animal, is the pair of long tubes (r\ which are attached to the 

 sides of the abdomen of the female ; these appear to be receptacles 

 for eggs, and to be analogous to the capsules of the Cyclops, &c. 

 (Fig. 599). The Caligi are parasitic upon marine fishes, upon 

 the skin of which they are able to creep about freely. They can 

 also swim, but are far less active than the Arguli. It is supposed 

 that they do not feed on the blood of the Fishes to which they 

 attach themselves; but rather on the mucus with which their 

 surface is covered. 



. 609. CALIGUS 



