Figure 2, Plate VII., taken from Rudolphi, exhibits a view of the animal which gives rise to the first variety of sturdy. It is the many-headed hydatid of the brain, _Coenurus Cerebralis_ of naturalists. Like the _Cysticercus tenuicollis_, already described under the head of Rot, it consists of a thin membranous cyst, full or otherwise of serous fluid; but, unlike the aforementioned animal is studded over with groups of little velvety appendages or heads, each of which has a series of barbs projecting round the mouth. Figure 2, _a_, Plate VII., is a highly magnified representation of two of these heads. A good idea of the hydatid, as it exists in the sheep, may be derived from an inspection of Fig 1. Pl. VIII., which has been engraved from a sketch kindly furnished to me by my friend Dr Kirk of Deal. Fig. 1 represents the brain of a sheep two years old, which has been affected with sturdy. The right lobe, _a_, of the cerebellum or lesser brain, is much distended with fluid, which is enclosed in a membraneous bag, as shown at _b_, where an incision has been made to expose it, and at _c_, where it is shining through one of the coverings of the brain, the pia mater. The hydatid is found of all sizes, from that of a pea to that of Fig. 2, Plate VII. Large ones are far from rare, and the ventricle is frequently enormously distended. The hydatid in the brain from which Fig. 2, Plate VIII. was taken, though not filled to repletion, contained ten drachms of serum. The ventricle was consequently much dilated, as shown at _a_ in that figure, and the usual course and size of the convolutions completely altered. Instead of being folded, like the intestines, upon themselves, they proceeded, as seen at _b b_, from back to front of the brain; while the furrows between them, which are, in the healthy animal, usually too shallow to be measured, were in several places as deep as the length of the lines at _c d_.