1905.1 



REGENERATIOX OF THE TAILS OF MICE. 



493 



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 

 vertebrse. 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-fia-. 70. 



Text-fie-. 71. 



Text-fig. 70. — Tail-vertebree and regenerated appendix of a species of 

 Central Asian Eliomys. 



Text-fic 



. 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 ap- 

 pearance presented by certain other skins of Grapidurus 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 



