An extraordinary communication has been made to the members of the Whitechapel Vigilance Committee. Mr. Lusk, builder, of Alderney Road, has received several letters purporting to be from the perpetrator of the Whitechapel murders, but believing them to be the product of some practical joker, he has regarded them as of no consequence. On Tuesday evening, however, he received the following letter in a cardboard box containing some fleshy substance:-- "From Hell, Mr. Lusk,-- Sir,--I send you half the kidney I took from one woman. I prasarved it for you. The other piece I fried and ate. It was very nice. I may send you the bloody knife that took it out if only you wait a while longer.--Signed, Catch Me When You Can." Mr. Lusk was at first disposed to think that another hoax had been perpetrated, but eventually decided to take the opinion of the Vigilance Committee. Yesterday that body desired to take the contents of the cardboard box to a medical man whose surgery was near. Mr. Read, assistant to Dr. Wiles, examined the contents of the box, and declared the substance to be half a human kidney, divided longitudinally. But in order to remove any reason for doubt he conveyed it to Dr. Openshaw, who is pathological curator to the London Hospital Museum. He examined it, and also pronounced it to be portion of a human kidney. He was further of opinion that it was the organ of a woman about 45 years of age, and it had been taken from the body within the last three weeks. It will be within the recollection of the public that the left kidney was missing from the body of the woman Eddowes, who was murdered and mutilated in Mitre Square. Mr. Lusk and another member of the Vigilance Committee took the parcel yesterday to Scotland Yard; but the police authorities there referred them to the detectives at Leman-street. At the latter place the officer who is directing inquiries took down Mr. Lusk's statement, which he considered to be of great importance, and the box and its contents were left in the care of the police pending further investigation. Mr. Lusk states that a day of two before receiving the box he had sent to him a post-card, which he now considers of sufficient importance to make public. It is in the following words:-- "Say Boss, you seem rare frightened. Guess I'd like to give you fits, but can't stop. Time enough to let you have box of toys. Play copper games with me. But hope to see you when I don't hurry too much. Good bye, Boss." The Vigilance Committee held another meeting yesterday, when this new feature in the case was considered.

After the discovery of the human leg in the vault at the new police buildings, the search for other limbs of the murdered woman which might be there secreted was resumed late on Wednesday night. A bloodhound, one of those which had been used in the Hyde Park experiment, was brought from King- street Police Station, and a staff of constables with Inspectors Peters and Marshall, were engaged for an hour and a half in turning over earth, but on the work being suspended at 10 p.m. no new discovery had been made.

Dr. Bond, divisional surgeon of the A Division, made a careful examination yesterday morning at Millbank-street of the portion of the leg found on Wednesday, and on comparing it with the trunk already in the mortuary, he is of opinion that it belongs to the same body. It is, however, in a better state of preservation, and this is accounted for by the fact that it has been sufficiently covered with earth to exclude the air, whereas the trunk was only wrapped up in a skirt. Dr. Bond is also of opinion that both portions of the body had been lying where found for over six weeks, not withstanding the statements made by people at the works that they were not there on the Friday or Saturday previous to their discovery, and the fact of the leg being in such good preservation is one point in his argument for holding this opinion.