The general form is elongated and somewhat hour-glass shaped, and the =centra= are convex in front and concave behind; an opisthocoelous condition such as this is quite exceptional in Anura. The =notochord= may persist intervertebrally[54], but in the centre of each vertebra it becomes greatly constricted or altogether obliterated, and replaced by marrow. The superficial portion of the centrum is ossified, while the articular surfaces are cartilaginous. The =neural arches= are low and articulate together by means of =zygapophyses= borne on short diverging processes. The anterior zygapophyses look upwards, the posterior downwards. Each neural arch is drawn out dorsally into a very slight cartilaginous =neural spine=. On each centrum, at a little behind the middle line, there arise a pair of short backwardly-directed =transverse processes=; each of which becomes divided into two slightly divergent portions, a dorsal portion which meets the tubercular process of the rib and is derived from the neural arch, and a ventral portion which meets the capitular process of the rib and is derived from the ventral or haemal arch. The division between these two parts of the transverse processes can be traced back as far as the sacrum. The =first vertebra= as already mentioned differs much from all the others. It has no ribs, and presents anteriorly two slightly divergent concave surfaces which articulate with the occipital condyles of the skull. Between these surfaces the dorsal portion of the anterior face of the centrum is drawn out into a prominent =odontoid process=, the occurrence of which renders it probable that the first vertebra of the newt is really the axis, and that the atlas with the exception of the odontoid process has become fused with the skull. The sacral vertebra or =sacrum= differs from the vertebrae immediately in front of it only in the fact that its transverse processes are stouter and more obviously divided into dorsal and ventral portions. THE CAUDAL VERTEBRAE. The =caudal vertebrae= are about twenty-four in number. The anterior ones have hour-glass shaped centra, and short backwardly-directed transverse processes. The middle and posterior ones have rather shorter centra, and are without transverse processes. The neural arches resemble those of the trunk vertebrae, but each is drawn out into a rather high cartilaginous neural spine abruptly truncated anteriorly. All the caudal vertebrae except the first have also a haemal arch, which is very similar to the neural arch, and is drawn out into a haemal spine quite similar to the neural spine. Both neural and haemal arches are ossified continuously with the centra. B. THE SKULL. The skull of the newt is divisible into three principal parts:-- (1) an axial part, the =cranium proper=, which encloses the brain and to which (2) the =capsules= of the =auditory and olfactory sense organs= are fused;