300 



APPENDIX. 



in breadth, of a milk-white colour, subpellucid, subcylindrical, con- 

 tractile like a worm, soft, without limbs or processes ; but when 

 magnified, the margins appear crenulate, from the skin being drawn 

 mto circular wrinkles. The anterior extremity 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 



No. XLIX. — Udonella Caligorum. 



a. Natural size, attached to a portion of the caudal filament of the Caligus. 



b. The saine magnified. 



c. A single specimen compressed between plates of glass, and highly magni- 



fied ; the proboscis is thrust out of the mouth and forwards. 



d. A cluster of ovaries magnified. 



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 course and termination could not be 

 traced with any degree of accuracy. Half-way between the mouth 

 and the first circular spot, there is an opake irregular mark, which 

 gives origin to the ovary, and which can be easily seen attached to a 

 vesicle in this spot, by its thread-like twisted pedicle. I have never 

 seen more than one of these in the same body, and I have seen it 

 extruded through an aperture at the side of, or near the mouth, as 

 is shown in two of the individuals figured. The ovaries are oval or 

 pear-shaped, and are filled with a granular matter ; they are attached 

 in clusters to the body of the Caligus by their pedicles, and may 

 usually be found in great numbers. 



