WEDNESDAY, APRIL 2np, 1890. 
MR RY (GsoCRAN By ckyG:Si, 
ON 
SPHENODON AND ITS AFFINITIES. 
Among the most noteworthy of the recent additions to the 
Brighton Museum purchased by means of the Clericetti bequest, 
are the stuffed specimen and skeleton of the Sphenodon. This 
curious little lizard has become nearly extinct on the main land of 
New Zealand, chiefly owing to the introduction of pigs by the 
colonists. ‘These animals devour them, and they are also killed 
by the natives for food; but they are still to be found on the 
small islands off the coast in the Bay of Plenty, and are quite 
harmless, never attempting to bite or resist when captured. The 
structure of the skull presents some remarkable characters ; the 
quadrate bone is united sutrally and is immovably fixed to the 
_skull. It has a complete orbital ring and an expanded columella. 
The bottom of the orbit is entirely ossified. The frontal bones 
are united by a distinct suture, a groove running along their lower 
- edge for the reception of the olfactory nerve. The roof of the 
palate is almost continuous. The eyes are surrounded with 
sclerotic plates similar to those of the /chthyosaurus, and of some 
birds and fishes. In no other reptile do the skull and pectoral 
arch present so many similar features to those found in the two 
oldest yet known crocodiles Se/edon and Stagonolepis of the 
Triassic epoch. To compensate for the firm attachment of the 
os quadratum to the skull, the symphisis of the mandibles of the 
lower jaws is united by a fibrous ligament, and the bases of the 
upper jaws are concaved and move on a convexed ridge surface 
of the lower jaws. This enables them to move backwards or 
forwards, and helps mastication, which would not be possible were 
the lower jaws firmly united at the symphisis. 
The dentition of Sphenodon is very curious. When young 
it has four incisor teeth in each jaw, which co-ossify in old age, 
and then form only two in each jaw, which are wedge-shaped, 
hence the name of the genus. There are two rows of teeth in the 
upper jaws, close together, forming a groove for the reception of 
lower ones, and they are anchylosed to maxillary and palatine 
bones, and have a sharp cutting edge. Sphenodon has biconcave 
vertebre like fishes, uncinate processes attached to the ribs as in 
