Newaan.—Notes on the Physiology and Anatomy of the Tuatara. 223 
The dark form is found in the N orth; the intermediate at East Cape 
Island; and the lightest form in the South. 
Sphenodon punctatum was the form so elaborately described by Dr. 
Günther. The other species has not been anatomically examined. 
Classification of Sphenodon. 
At present the position of the Sphenodon in the Sauropsida is not yet 
quite certainly known. To meet the difficulty Dr. Giinther proposes the 
following division of recent Reptilia :— 
I. Squamata. II, Loucata. III. Cataphracta, 
He divides the Squamata into Ophidia, Lacertilia, Rhynchocephalia. If 
external characters alone were considered, he says it would most resemble 
Ayamide, of which genus Professor Peters thinks it merely an aberrant form. 
Professor Seeley talks of Lacertia, Rhynchocephalia, and Crocodilia. In his 
** Forms of Life," Rolleston talks of it as a “low lizard.” 
Huxley divides the Lacertilia into various groups :—I. Pterygoid and 
quadrate bones united. II. Pterygoid and quadrate bones disunited. 
Class I. he divides into A., a columella and inter-orbital septum; and 
subdivides it into those with amphieclous and those with procelous 
vertebrea—Kionocrania amphicelous and Kionocrania procelor. Those with 
amphieclous vertebre are again divided into Acrodont or Pleurodont, and 
Thecodont. There are three Orders: <Acrodont or Pleurodont Acalabota, 
Rhynchocephalia, and Homeosauria. 1 
Relationship with extinct Reptilia. 
So far as is yet known the relationship between the Sphenodon and 
extinct reptiles is of great interest. Lyell writes :*—“ The Hyderapedon 
was afterwards discovered in beds of about the same age (upper trias or 
keuper) in the neighbourhood of Warwick and also in South Devon, and 
remains of the same genus have been found in Central Italy and Southern 
Africa, in rocks believed to be of triassic age. It has been shown by 
- Professor Huxley to be allied to the living Sphenodon of New Zealand. The 
recent discovery of a living saurian in New Zealand so closely allied to this 
supposed extinct division of the Lacertilia seems to afford an illustration of 
a principle pointed out by Mr. Darwin of the survival in insulated tracts, 
after many changes in physical geography, of orders of which the congeners 
have become extinct on continents where they have been exposed to the 
severer competition of a larger progressive fauna.” Professor Huxley also 
discovered that the extinct lizards of the triassic age, viz., Rhynchosaurus 
and the Hyderapedon, were both closely allied to this Sphenodon. Still 
more recently, in Illinois, certain fossil reptilia have been found which 
possess a feature common alike to the Archegosaurus, stegocephalic batra- 
* * Student's Elements of Geology,” 349. 
