1911 Encyclopædia Britannica/Sphenodon
SPHENODON, or Tuatara. Sphenodon s. Hatteria (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 jdeally 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, the 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. (1881), xiv. 276; 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. 1-86, six plates; A. Dendy, Quart. Journ. Mic. Sci. (1899), 42, pp. 1-87, ten plates and ibid. pp. 11-153 (parietal eye); H. Schauinsland, Arch. mikr. Anat. (1900), 56, pp. 747-867, plates. For anatomy. A. Günther, 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. G.)