226 Transactions. — Zoology. 



behind tliem, just as a dog does when scratching out a rat-hole. Giinther 

 objects to the behef that they burrowed, because he says theu* fore-hmbs 

 are slender ; but the skeletons in the Colonial Museum show that they are 

 not very slender, and are certainly strong enough and stout enough to be 

 used for burrowing in loose soil. The long sharp claws too are admirably 

 adapted for penetrating deejp into loose sand or light loam. The claws are 

 sharply carved out on their posterior aspects. They soon become blunted 

 when used against the wooden or tin walls of a cage. The dorsal spines 

 are no hindrance when entering holes, because they are very soft, being 

 easily bent on themselves or pressed down on one or other side. 



Locomotion. 



Dr. Giinther elaborately described the abdominal ribs, and, speculating 

 on their use, inferred that their special function was " to assist in locomo- 

 tion." He thought that by beuag approximated these ribs would assist the 

 animal in crawling over rocks, especially as to each of the ribs (twenty-five 

 or twenty-six in number) was attached a row of scales, the ends of which, 

 he thought, were tilted iip, thus causing a roughened abdominal surface, 

 which would also help the animal. When dissecting a tuatara, it seemed 

 to me that the amount of approximation between the ribs must be 

 infinitesimal, and therefore these ribs could not be subservient to the 

 special function of assisting in locomotion. I therefore carefully studied 

 the motions of living tuataras, to ascertain which view was correct. 



Tuataras are very lazy in all their movements, and even when frightened 

 they move very slowly. Thek usual pace is a very slow crawl, the abdomen 

 and tail trailing on the ground. The femora are articulated at right-angles 

 with the pelvis, and the tibiee and fibise at right-angles to the femora ; tliis mode 

 of articulation causes a great strain on the muscles of the posterior limbs, 

 therefore when at rest the trunk rests on the ground. I tried many experi- 

 ments v/ith mine and narrowly watched their movements. When driven 

 fast, or when chasing prey, they always lift the whole trunk of the ground, it 

 does not touch at any spot. This rapid gait is very " wobbling," something 

 like a man swimming sideways. After running three or four yards they 

 grow weary and stop. They cannot jump the smallest obstacle, their limbs 

 being too feeble. In ordinary crawling they propel themselves by means of 

 their limbs alone, and the abdominal ribs take no part in these movements, 

 though trunk and tail rest on the ground. The abdominal ribs are not used 

 during either slow or rapid movements, the limbs doing all the work; the 

 limbs are quite strong enough to di-ag the body and tail along the ground, 

 and during more rapid but very brief movements are powerful enough to 

 lift the body and great part of the long heavy tail off the ground. 



If a tuatara be lying with its abdomen across the edge of a plate 



