250 PARASITES. 



tify from my own knowledge. Possibly fresh-water, which is speedily 

 fatal to most marine animals, does not spare the Caligus. 



The Caligus of the Salmon is somewhat larger than that of the Cod, 

 the shield rudely and obtusely quadrangular, with faint indications of 

 compartments. Thus the parts of the shell are more solid, and the 

 ovarian tubes very long. 



Total length of the animal two inches, whereof the body occupies 

 half an inch, by two lines in breadth. The ovarian tubes an inch and a 

 half. Colour of this subject, dark brown. 



PLATE LXVII. 



FIG. 1. Caligus salmonis, slightly enlarged. 



3. CALIGUS. Plate LXVI. fig. 8. 



This animal, which I had reason to consider a Caligus, was attached 

 by a long ligament to the anterior part of fig. 3. I had never seen it 

 before nor since, and being much smaller than the figure in the plate, 

 which is enlarged, I conjectured it might be one of the young in an in- 

 termediate stage, advancing to metamorphosis. Nothing followed, how- 

 ever, to corroborate this conjecture, and I should have omitted the sub- 

 ject entirely, had I not observed it alluded to as a distinct species in the 

 recent valuable work of Mr Adams. 



PLATE LXVI. 



Fio. 1 . Caligus curtw ? enlarged. 



2. Four specimens somewhat under the natural size. 



3. Female Caligus, antennular organs, a ? ovarian tubes, b ; upper 



surface, enlarged. 



4. The same, under surface. Here the feet are indistinctly seen. 



enlarged. 



5. Lower portion of another female, more enlarged. Leech, a ; 



ovarian tubes, b. 



6. Embryos in their integument, enlarged. 



7. Young Caligi free of their integument, enlarged. 



8. Caligus, originally attached to fig. 3, enlarged. 



9. Capsules of unknown nature, full and empty, enlarged. 



1 0. Zoophyte growing on a living Caligus, enlarged. 



11. Leech, a ; seated on an ovarian tube, b, enlarged. 



