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Show 1905.] REGENERATION OF THE TAILS OF MICE. 4 9 3 similar to that in Lizards, there being a central tube filled with soft or cartilaginous matter, and surrounded by a cylindrical bony envelope, of similar appearance and texture to the true caudal vertebrae. A proper microscopic examination and report would, it was hoped, be made by Dr. Ridewood. In the third specimen from the French Congo the tail had been broken at about a third of its length, and the regenerated terminal vertebra, with its spike, measured 15 mm. in length. Text-fig. 70.-Tail-vertebrse and regenerated appendix of a species of Central Asian JSliomys. Text-fig. 71.- Tail of a species of Graphiurus from Fernando Po showing regenerated appendix. It seemed clear from these specimens, from the type of Claviglis crassicaudatus, as described by Dr. Jentink, and from the appearance presented by certain other skins of Graphiurus in the Museum Collection, that in the not uncommon event of losing part of their tail, Dormice-perhaps of all species-were able to supply the place of the lost part by swelling up what remained into a club-shaped organ, clothed externally with abnormally long hairs, and supported internally by an elongated rod of bone growing out of the vertebra in which the break had occurred. Such a regeneration would be of essential value to the animal, for, in climbing, the tail was used as a balancer, and, if broken off Text-fig. 70. Text-fig. 71. ) |