H.—4.

recognised by all zoologists as a sufficiently accurate authority. The characters of the Tania serialis are taken from my own examination of the tape-worms reared in dogs fed with the Ccemirus of the rabbit. At first sight the two tape-worms seem to be singularly alike ; but careful measurements show a sufficient number of differences. As is well known, there is often considerable difficulty in distinguishing the different species of tape-worm, owing to such resemblances, so that the apparent similarity of the two now under consideration need not be deemed to prove their identity. T. ccenurus is said to be 30cm.-40cm. (12in.-16in.) in length. I have found T. serialis 40cm.60cm. long, and sometimes longer. 27. serialis has not more than a hundred and fifty segments before the first ripe one, using the term " ripe " in its narrower sense (v. supra) : T. ccenurus has nearly two hundred. The number of hooks in T. aerialis is twenty-eight to thirty*—more frequently thirty :in T. ccenurus it is usually twenty-eight, but varies from twenty-four to thirty-two. The larger hooks are smaller in T. serialis than in T. ccenurus, being o'lsmm. long in the former and o'l6mm. in the latter; the small hooks are much the same size in both, being from 0'096mm.--0-101mm. in T. serialis and O'l in T. ccenurus. A comparison of the hooks of T. serialis (see Plate 11., fig. 12) with those of T. ccenurus (fig. 11, reproduced from Leuckart) shows that they differ both in curvature and in other minor points. In T. serialis the curved and pointed end is not so nearly in the same straight line with the posterior root of the hook, and there is a constriction near the base of the curved part. The points described as specially characteristic of the hooks of T. ccenurus —viz., the heart-shaped form of the anterior root of the large hook, and the slenderness of the posterior root of the small hook—are not characteristic of the corresponding parts in 1. serialis. It must be mentioned, however, that the hooks show some variety in these minor points. The ripe segments appear to be distinctly larger in T. serialis, and the uterus, with its branches, covers a smaller proportion of the width of the segment than in T. ccenurus. (Compare fig. 10, Plate 11., a segment of T. cmnurtis, magnified 10-15 diams., after Leuckart, with figs. 8 and 9, of segments of T. serialis, magnified 6J diams.) The above points will be sufficient to show that anatomical differences do exist; but we cannot expect to find very wide differences between the two tape-worms, for the fact that both have larval forms of the Coenurus type proves that they are closely allied, and may therefore be expected to show a general resemblance to one another. (c.) The most conclusive evidence, however, is to be derived from feeding-experiments on the sheep. If T. serialis is really identical with T. comurus, then the eggs of T. serialis should, when administered to a sheep, give rise to a bladder-worm in the brain, and produce the disease known as " gid." Ccemirus cerebralis is more particularly found in young sheep. I obtained, therefore, the youngest sheep available at the time of the year, which was just before the lambing-season. The sheep must therefore have been ten to twelve months old. It received at different times some forty to fifty proglottides of tape-worms reared from the C. serialis of the rabbit— i.e., it must have received over a million eggs. Nevertheless the sheep showed no sign of " gid," and, when finally dissected some throe or four months later, showed no trace of bladder-worm in brain, muscles, or any other part of the body. A few months later another lamb, four or five months old, was obtained, and eggs of T. serialis were given to it. At the time of writing the lamb is still perfectly healthy. It appears to me that the evidence brought forward is amply sufficient to demonstrate that the Ccenurus of the rabbit is specifically distinct from that of the sheep. 6. Smaller Bladder-worm of Babbit (Cysticercus pisiformis). It will be desirable to make a brief reference here to this small bladder-worm, though it was only found by me twice in rabbits from the Wairarapa, and always in small numbers. But in wild rabbits captured in the Waikato for the purpose of experiments this well-known Cysticercus was almost always found—generally only from one to half a score specimens in a rabbit. One rabbit, however, formed a marked exception, for it contained over four hundred small cysts, of which over two hundred were counted on the great omentum. This bladder-worm is round, and about the size of a pea—hence its name of pisiformis. It is a very familiar form in Europe, and is the larval or cystic stage of Tcenia serrata, a tape-worm of the dog. I have found the tape-worm in dogs in the neighbourhood of Auckland. The earlier stages in the development of the Cysticercus pisiformis are passed in the rabbit's liver; it then makes its way out of that organ, and, after passing a certain time free in the abdominal cavity, it becomes encysted and attached to the peritoneum, especially to the folds which form the great omentum and to the peritoneal covering of the rectum. "Whilst present in small numbers it causes very little injury to the rabbit, but there is reason to believe that when very large numbers develop simultaneously serious disturbance is produced in the liver. It must be seldom, however, that this parasite can, under conditions obtaining in nature, cause the death of a rabbit. 7. Liver-coccidia of the Babbit. I have already stated in my interim report that a considerable proportion of the rabbits examined by me in the North Wairarapa were more or less affected with a disease caused by minute animal parasites belonging to the group of Gregarinida, and known as Coccidia (Coccidium oviforme). It will be unnecessary for me to repeat here the description already given in a previous report. The Coccidia undergo development in water or in moist places, the contents of each Coccidium breaking up and transforming into four oval spores. Each spore has a delicate membranous wall, and contains a curved rod-like body, with thickened ends, whilst against the concavity of the curve rests a round granular mass, which, with osmic acid and picrocarmine, stains more deeply than the rod-like body. The rod-like body is believed to be the true germ.

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