Udoii clla Caligbrum . 



497 



a, Udonella Caligbrum, of the natural size, attached to a portion of the caudal filament of the 

 Callgus ; b, the same magnified ; c, a single specimen compressed between plates of glass, 

 and highly magnified ; the proboscis is thrust out of the mouth and forwards ; d, a cluster 

 of ovaries magnified. 



hangs in clusters from the caudal filaments, waving and con- 

 torting itself like a worm in pain. I have not seen it vo- 

 luntarily leave its hold, but it maybe removed without difficulty 

 or injury, when it lies very helpless in the basin and ap- 

 parently incapable of progressive motion. In its structure it 

 seems allied to some intestinal worms, but from its habits 

 there is reason to locate it among the Uirudines, although 

 it should be remarked that the Caligus did not appear to have 

 become thin and exsanguinous, and swam about with its load 

 of blood-suckers with great activity, indifferent to their wrig- 

 glings and annoyance. 



Udonella Caligorum is about 4 lines in length, and scarcely 

 one in breadth, of a milk-white colour, subpellucid, subcylin- 

 drical, contractile like a worm, soft, without limbs or processes; 

 but when magnified the margins appear crenulate, from the 

 skin being drawn into circular wrinkles. The anterior ex- 

 tremity is truncate, with a sort of thickened wart at each side : 

 the mouth is inferior (not terminal), forming a longitudinal 

 slit from which there is occasionally extruded a very short 

 thick proboscis plaited round the rim, but edentulous : and 

 the sucker at the posterior extremity is circular, cupped, and 

 plain. If the body is now slightly compressed between plates 

 of glass, we perceive near the middle a clear circular spot, 

 or viscus, containing translucid granules, and immediately 

 under this there is another bag, or viscus, about twice the size 

 of the former. The largest appears to be the stomach ; and 

 the intestine is seen obscurely to form numerous convolutions 

 in the space between it and the sucker; but their particular 



