Newman.—Notes on the Physiology and Anatomy of the Tuatara. 227 
or the ridge of a stone it cannot wriggle itself off ‘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 
posterior 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 climbs up rocks the ribs are powerless, and afford the limbs no 
help. I am of opinion that the ribs are useful not £o 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 
vertebra they form a strong, compact and yet mobile case. 
Günther 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 pes and manus and not on its digits and 
claws. ltis 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 limbs 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 Lacertilia (Lacerte iguane geckos) the 
caudal vertebre 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 plane 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 injured part will heal, but distinct 
