Maddox, on Parasites of the Common Haddock. 91 
In the interior is noticed a large, dark-looking sac, occupying 
a great portion of the inside of the creature, extending along 
the two lower thirds in a sigmoid or partially curved direc- 
tion, and terminating at a distinct posterior outlet ; looking 
almost black by transmitted light, and by reflected light of 
a dead white ; the contents of this sac are made up of minute 
globules of a highly refractive character, and I believe of an 
also albuminous matter enclosing air. Within the sac, in the 
living creature, these minute globules may he seen in irre- 
gular motion, and occasionally a portion is emitted at the 
outlet. Whether this is to be regarded by some as a respira- 
tory sac or urinary apparatus, or whether it belongs to the 
digestive system I am not certain, or whether it is not con- 
vertible at some future stage of the creatures existence into 
some important and defined organ, is doubtful. It exists 
more or less in all, though in the most minute examined it is 
exceedingly trivial. The large circular disc at the anterior 
extremity of the creature has numerous fibres or folds, 
circular and radiating, with an aperture that varies from 
a circle to a sharp elipsoid, which, from analogy in the 
other distoma, we may regard as a mouth, — though, from the 
density of the superposed structures, I have never fairly seen 
an oesophageal tube, — I have noticed only, as in the fig. 4, 
indications of such being present. Below the anterior disc 
on either side of the body, are small irregularly placed 
cellular bodies ; I have counted sixteen on one side, but 
could not make out the same number distinctly on the other 
side, made up of nucleated cells, or if we regard the cell as a 
single structure, with about eight or more nuclei. These were 
not noticed in any specimen before staining some of the 
creatures by Dr. Beale’s plan, when they were quickly re- 
cognised and are figured in fig. 4, those the lowest in the 
body are the most distinct, the largest and most nucleated in 
their structure. Are^they unimpregnated ova, or yelk glands ? 
These bodies are best seen on the dorsal aspect, though in 
no single case have I found them symmetrical, the parasite 
dying in some contrary position, though placed as such in 
the figure, which is made up in one or two of its internal 
organs from an extended series of observations on various 
examples. (My best specimen I lost from slightly warming 
the mounted slide, the glycerine appearing to act on the 
delicate sarcode structure of these bodies as a solvent. This 
is named as a caution to others.) Situated more centrally 
are two tubes which appear to be united below the anterior 
disc by a cross branch, of which, however, I am not absolutely 
certain, the parts being much obscured ; as they extend 
