The larval stage of Taenia taeniaeformis, namely, Cysticercus taeniae-taeniaeformis, has recently been described by the writer (1951), a detailed account being given of the musculature and of the excretory and nervous systems of the scolex and strobila. In addition, some abnormalities in structure were noted, chief of which was the spiral torsion observed in some specimens and which involved the musculature, excretory and nervous systems of the strobila but not the surface layers. A search was then made for some adult specimens in order to find whether the same abnormality could be seen and to ascertain what the effect of such a torsion would be on the genitalia in the mature and gravid regions. Several adult specimens, from the intestine of a cat, were given to the writer by Mr L. E. Hughes, veterinary investigation officer. Unfortunately, none of these specimens showed the identical spiral torsion found in the larva, but two of them had become knotted together, presumably at an early stage, and were considerably distorted in the regions involved in the knot. This distortion was again of a spiral nature but involved the entire proglottid and not only the internal structures as was found in the type of spiral torsion common in the larval stage of this species. The condition was not merely a turning over of the strobila but an abnormal spiral growth brought about by the continued constriction on the body where the two worms were twisted around one another. So here again, in the adult stage, spiral torsion is evident but from a different cause and involving the whole of the relevant segments from the surface layers to all the contained organs.