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It will be seen, therefore, that the bladder-worm disease in the rabbit is closely analagous to the hydatid disease, which is so common in man, particularly in the Colony of Victoria, and frequently proves fatal. In both cases the ova are derived from a tape-worm of the dog, and in both instances the ova give rise to large bladder-worms (or hydatids), in the one case in the rabbit, in the other case in man, or in the sheep, ox, pig, &c. The two kinds of bladder-worms, however, are distinct, and so, too, are the tape-worms, to which they respectively give rise. In some cases the presence of only a single bladder-worm may cause the death of a rabbit, for the worms are found in places where they must interfere with the vital functions ; for instance, in the heart or in the thorax, where the pressure on the lungs cannot be but injurious. I have found a worm in one of the muscles of the eyeball, causing displacement of the eye; and in one of my experimental rabbits I found one had settled in the tongue, and if the growth of this had been allowed to progress it must ultimately have caused the starvation of the rabbit by preventing it from swallowing. Although two are the largest number of bladder-worms found by me in any one rabbit under natural conditions, yet it is highly probable that rabbits do sometimes swallow a large number of eggs, and that the greater number of bladder-worms developed therefrom kill the rabbit. I may cite here, as an example which illustrates the point, the smaller bladder-worm (Cysticercus pisiformis) found in rabbits as mentioned above. In this case the conditions for infection are precisely similar, and yet it is seldom that a single bladder-worm only is found. More frequently from five to ten are present, and sometimes a still larger number. The larval form of the common tapeworm of a man (Tcenia mediocanellata) occurs as a very small bladder-worm in the flesh of the ox, beef containing these larvae being turned measley. Here many hundreds, or even thousands, of bladder-worms or measles may be found in the same animal. It may be said that if the bladder-worms kill any considerable number of rabbits such dead rabbits ought to be found lying about on the ground ; but many of them would doubtless die in the burrows, and so escape notice. The rabbiters in the Wairarapa informed me that they sometimes found dead rabbits lying about, but that the hawks had always been at them, so that it was impossible to discover what the rabbits might have died from. The disease has certainly been known in the district for over five years, and there is some evidence that it was present ten or twelve years ago. More than five years ago Dr. Hosking, of Masterton, procured a specimen, which he gave to Sir James Hector. I found only a small proportion of the rabbits affected with the disease in the places I visited, but the rabbiters state that it is no uncommon thing for them to find 20 per cent, of the rabbits with bladders. The men would only notice the advanced stages of the disease, so that a much larger percentage of the rabbits may really be affected. There is, however, a great deal of difference in this respect in neighbouring localities, and in the same locality the disease may be common at one time and scarce at another. In one instance, four out of six rabbits shot on one occasion were affected with bladder-worm. At the Dry Biver run only one bladdery rabbit was obtained, but here, and again near Masterton, I found that the rabbiters were unconsciously doing their best to prevent the spread of the disease. Noticing that their dogs were infested with tape-worms, they periodically gave them medicine to expel the worms. This may, in part, account for the much smaller percentage observed by me. Parasitic diseases are eminently liable to variation, and although my own observations show that in the rabbits which came under my notice only some 5 per cent, were infested with bladder-worm, yet the large percentage said to occur by others is by no means improbable. The bladder-w-orm disease is doubtless one introduced from Europe, either with the rabbit, or more probably brought by the importation of a dog infested with the tape-worm. New Zealand was originally a country devoid of all mammals except bats until the Maoris brought the native dog and the native rat. Since then the colonists have introduced various animals, and at the same time many of the numerous parasites which infest those animals in European countries. Whilst engaged in investigating the parasitic diseases affecting sheep in New Zealand I found in one lamb no less than eight different kinds of parisitic worms, all of them forms known in Europe, and doubtless brought thence. We may, therefore, appropriately inquire whether any similar form of bladderworm has been observed in Europe, and whether it has been noticed as the cause of any considerable epizootic amongst rabbits. Species of Cocnurus, or many-headed bladder-worms, have been found in the rabbit in various countries ; amongst these there is a form occurring in the rabbits in the eastern counties of England, and first described by Bose in 1833. By the Norfolk Warreners rabbits affected by this bladder-worm are termed " bladdery." A specimen of a similar form is preserved in the Oxford University Museum under the name of Ccenurus cuniculi. Dr. Cobbald states that he obtained a specimen of the same form from Ayrshire. In Erance similar bladder-worms have been found in rabbits by various observers. M. Baiilet found in a rabbit a Ccenurus which had the size of a fowl's egg; the heads attached were very numerous, and arranged, not in groups, but in rows, and hence he termed the worm Ccenurus cerialis. Given to two dogs, the heads developed into tape-worms. I have pointed out above that the heads in the bladder-worms from the Wairarapa rabbits are sometimes arranged in groups and sometimes in rows ; the arrangement in rows may therefore be looked upon as an inconstant character. It appears to me highly improbable that the Ccenuri of the English and Erench rabbit-warrens and of the Wairarapa District belong to one and the same form. Ccenuri of similar characters have also been found in the muscles of the rabbit in Germany and Italy. Beference will be expected here to the disease which is said to appear from time to time among the Canadian rabbits (not the same species as the English rabbit), and to sweep them off in such numbers that, for the time, they seem to be exterminated. Sir James Hector, in a letter which has been published by Mr. Coleman Phillips, states that the disease is due to a bladder-worm. Whilst I desire to show all due respect for Sir James Hector's opinion, I think it right to say that from what