Newman. — Notes on the Plvjsiolor/ij and Anatomij of the Taatara. 227 



or the ridge of a stone it cannot wriggle itself oft' unless it uses its limbs. 

 The trunk is short and these twenty-five or more ribs are very close 

 together, the limbs not being far apart ; they are bound together by 

 large quantities of strong fibrous tissue, the amount of movement be- 

 tween each rib is very small, and when lifted off the ground and 

 twisting its body about, the ventral plates do not have their roughened 

 jDOsterior edges tilted up by approximation of these ribs. I think that the 

 abdominal ribs play no part in locomotion ; whether the reptile crawls 

 or runs or chmbs up rocks the ribs are powerless, and afford the limbs no 

 help. I am of opinion that the ribs are useful not to assist the limbs, but 

 to act as a broad, strong, abdominal sole. Any one who has dissected a 

 female tuatara with its eggs filling the whole abdomen, and has noticed the 

 enormous size of these eggs, would be convinced that the abdominal ribs 

 would be of the greatest use to the animal by supporting and protecting 

 them from injury. A tuatara carries ten large eggs, all about the same size 

 and weight, any two of these weigh as much as the whole of the other tho- 

 racic abdominal and pelvic viscera. These eggs lie in two parallel rows, 

 extending from the cloaca, almost to the farther end of the thorax, they lie 

 on these ribs, which support them, for the ligaments which attach the ovi- 

 ducts to the spine are thin and long. By this means the unusual weight is 

 well distributed over the body. When crawling over the edges of sharp stones 

 the ribs would protect the eggs and other viscera ; with the true ribs and 

 vertebrae they form a strong, compact and yet mobile case. 



Giinther also says the sharp claws " show that in a normal state they 

 cannot be much used in dragging the heavy body or even in burrowing," 

 but this is a statement founded on a misconception of their mode of progres- 

 sion. The tuatara walks on its ^Des and manus and not on its digits and 

 claws. It is plantigrade not digitigrade, as indeed might easily be learnt 

 from examination of the skin and its scales which cover those parts. When 

 the animal is at rest the long nails keep the digits off' the ground, and almost 

 all the pressure of the hmbs is on the pes and manus ; the abdomen and 

 tail rest on the ground wholly unsupported by the limbs. 

 Tail fracture and reproduction. 



Of great interest is the subject of tail reproduction in tuataras. Pro- 

 fessor Huxley says that "In many LacertiJia (Lacertm iguan(E geckos) the 

 caudal vertebrae have a very singular structure, the middle of each being 

 traversed by a thin unossified transverse septum. The vertebra usually 

 breaks with readiness through the i^lane of the septum, and when such 

 lizards are seized by the tail that appendage is pretty certain to part at 

 those weak points." Knox discovered that this curious feature obtained 

 in the tuatara; he also learnt that the injm'ed part will heal, but distinct 



