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birds, a rounded clavicle and a T shaped interclavicle like 
Ornithorhynchus and Ichthyosaurus. The sternum and abdominal 
ribs are more developed than in any other reptile. All the earlier 
lizards at present known had biconcaved vertebral centra, while 
all but a few of the existing species have the centra hollow in 
front and convex behind. 
The nearest allies of Sphenodon are Ayperodapedon and 
Rhynchosaurus. These fossil forms are found in the Triassic 
formation, and differ from all other lizards recent and fossil, in 
the massive beak-like structure of the jaws, with maxillary and 
palatal teeth running in a groove for the reception of the lower 
jaws. The abdominal ribs are greatly developed. The vertebral 
system of the lizards has undergone a change corresponding to 
that which has occurred in that of the crocodiles. Lacertilia 
existed in the Paleozoic epoch, differing less from Sphenodon 
than they did from Ayferodapedon and Rhynchosaurus. A new 
fossil lizard allied to Sphenodon has been discovered in the 
Permian beds near Dresden. It has been described by Dr. 
Herman Credner of Leipsic, under the name of Ka/adiosaurus 
priscus, or “the ancient stilt walker,” so named from the length 
and slimness of the limb bones, which are proportionately longer 
and more slender than those of the Palzo-hatterian group, to 
which some authorities consider Sphenodon belongs. 
In dissecting a specimen of Sphenodon one finds on remov- 
ing the skin from the top of the skull a small hole called the 
parietal foramen. Mr. W. B. Spencer recently discovered this to 
contain a rounded substance which upon careful examination 
proved to be an eye, with retina, pigment, lens, and a nerve en- 
veloped in connective tissue passing from the foramen to the inter- 
brain, and he found a continuous nervous connection between 
this single eye and the pineal gland. This nerve has apparently 
disappeared in the majority of other reptiles and amphibia. _ It is, 
however, also present in the Iguana, the common Chameleon, and 
Lacerta ocellata. In the cerebral hemisphere of the human brain 
there is a similar globular body about the size of a pea. Till 
within the last few years no idea could be formed as to its nature, 
but it is now considered to be an organ of sight, and the last 
trace of the single cerebral eye formerly characterising our remote 
one-eyed ancestors. There are certain marine animals ranging 
from the Arctic to the tropical seas called Ascidians or sea squirts, 
because when left dry on the rocks they eject water if touched. 
One species, Phallusia, resembles a leather bottle with two necks ; 
water is constantly passing in at one orifice and out at the other. 
Beneath the outer covering there is a soft animal with a large per- 
forated gill-sac, and below the gill-sac lies a spindle-shaped heart, 
a simple tube exhibiting a remarkable peculiarity. It contracts in 
alternate directions, pulsating first from back to front, resting 
