20 



thoracic, abdominal, lumbar, and sacral vertebrae, but again appearing between 

 the thirty-fourth and thirty-fifth vertebrae, rapidly increasing in size, (forming 

 a safe canal for the blood vessels), and gradually decreasing, together with the 

 neural and articular processes, until the centrum appears like a minute 

 cylinder, divided in the middle of its length, indicating the part which gives 

 way when the tail is accidentally injured. This fissure can be observed in the 

 thirty-eighth vertebra, and a separation may consequently take place in any of 

 the remaining vertebrae. From the peculiar form of the medulla spinalis, I 

 feel assured, that when injured, the complete vertebrae will not be reproduced, 

 but will present the appeai-ance as seen in the skeleton No. 1, in which the 

 total number of vertebrae is fifty ; and the termination of the tail is composed 

 of a deposit of earthy matter of about one inch in length. The series of 

 triangular processes, considered by Dr. Giinther as true ribs, — similar to the 

 false or floating ribs in the mammalia — appear to me, after a careful removal 

 of the integuments, to be dermal productions, much resembling those rib-like 

 processes as seen in the engraving of the Plesiosaurus. 



Art. III. — On the Anatomy of the Naultinus Greyii, Gray, or Brown 

 Tree Lizard of New Zealand. By F. J. Knox, L.R.C.S.E. 



[Read before the Wellington Philosophical Society, August 14, 1869.] 



During the month of January, 1862, a specimen of this reptile was sent to 

 me by a friend, and I examined it with great care. Many points of great 

 interest presented themselves to me, more especially the separation of the tail. 

 In an animal so highly organized, more especially in the skeleton, it appeared 

 to me to be an impossibility, that the complex mechanism of so important a 

 part of the animal economy should be suddenly removed, and not only the life 

 of the animal in no way jeopardized, but that the tail, in its entirety, would be 

 reproduced. Nay, more, that the animal had been seen, after the violent 

 separation of the tail, to search for it, and stick it on again ! I found, on careful 

 dissection, that the statement, in so far as the detaching of the tail from the 

 body, was correct, but that the separation not only occurred at a particular 

 part of the spine, but presented an obstacle to its regeneration, which appeared 

 to me, and still appears, impossible. I found the divided or separated surface 

 finely dovetailed ; the one (proximal extremity of the skin) presenting no 

 dentations, but a perfectly smooth margin ; the scales surrounding the part 

 arranged in symmetrical order, whilst on the separated part or tail, eight 

 wedge-shaped processes projected beyond the skin of the tail. (See preparation 

 of the dried skin.) These eight processes were entire, and not caused by a 

 tearing process, but were arranged in pairs : — 



Dorsal margin ....... 1 pair 



Abdominal margin ...... 1 ,, 



Lateral margin . • . . . . . 2 ,, 



Total ... 8 



As I attentively observed the separation of the tail, I found that a 

 delicate white cord was gradually leaving a canal in the tail portion. This I 

 recognised to be the medulla spinalis (see preparation in phial), and necessarily 

 rendered, in my belief, the power of reproduction still less possible. I may add 

 that the tail in the living animal is in no respect brittle, as stated by some 



