SPHENODON, or TUATARA  . Sphenodon s . Halteria (called by Gray after Hatter), with one species, S. punctatum, is the sole surviving member of the whole group of Rhynchocephalia (q.v. under REPTILES, Fossil) . It is one of the few reptiles inhabiting New Zealand; formerly common on the main islands, now restricted to some of the small, uninhabited islands in the Bay of Plenty, where these last " living fossils " enjoy the protection of the government . The Maoris call it ruatara, tuatete or tuatara, the latter meaning " having spines." This creature represents an almost ideally generalized type of reptile . The total length of large males is more than two feet, but mature females are scarcely half this size . In general appearance they much resemble the Agamidae, especially Uromastix, or Physignathus, with the massive head, the chisel-shaped front teeth, short legs and erectile crest of cutaneous spines on the head and along the mid-line of the trunk and tail, whilst the rest of the dark olive-green skin is granular, with yellowish specks . But the Agamoid resemblance is only skin-deep, and only the tyro can confound them with any group of Lacertilia . At the same time it is probable that Sphenodon stands near the ancestral root of the Lacertilia, before these divided into geckos, chameleons, and lizards proper . Sthe development of this animal has been first studied by G . B . Howes, who quotes the literature bearing upon the whole subject .

A

good account of the habits of the tuatara has been given by Newman . They live upon animals, but these are only taken when alive and moving about, e.g. fish, worms, insects . Sluggish in their habits, they sleep during the greater part of the day in their self-dug burrows, and are very fond of lying in the water, and they remain below for hours without breathing . Each individual excavates its own hole, a tunnel leading into a roomy chamber, lined with grass and leaves; part of the habitation is shared socially by a family of petrels, which is said to occupy usually the left side, whilst the tuatara itself lives a solitary life . The male croaks or grunts much during the pairing season; the hard-shelled, long-oval eggs, about 28 mm. long, are laid in holes in the sand, about ten in one nest, from November to January or February . They contain nearly ripe embryos in the following August, but they are not hatched until about thirteen months old; in the meantime they seem to undergo a kind of hibernation, their nasal chambers becoming blocked with proliferating epithelium, which is resolved shortly before hatching during the southern summer . In spite of their imposing, rather noble appearance, when, with their heads erect, they calmly look about with their large quiet eyes, they are dull creatures, but they bite furiously . For life history see A . K . Newman, Trans . New Zealand Inst . (1878), x .

222; Von

Haast, ibid . (188,), xiv . 2.76; Reischek, ibid. xiv . 274; A . Dendy,.ibid . (1899), xxxi . 245; Nature, 59, 340, For development; G . B . Howes and H . H . Swinnerton, Trans . Zool .

Soc . (1900), xv. i—86, six plates; A . Dendy, Quart . Journ . Mic . Sci . (1899), 42, pp . 1—87, ten plates and ibid. pp . 111—153 (parietal eye); H . Schauinsland, Arch. mikr . Anat . (1900), 56, pp .

?47—867, plates . For

anatomy: A . Gunther Phil . Trans . (1867), 157, pp . 595—629, plates; A . K . Newman, quoted above; F . J . Knox, Trans . New Zealand Inst . (1869) ii .

17—20; G . Osawa, Arch. mikr . Anat . (1898), 51, pp . 481—690, and ibid . 52, pp . 268—366 . (H . F .