Newaian. — Xotes on the Physiology and Anatomy of the Tuatara. 223 



The dark form is found in the North ; the intermediate at East Cape 

 Island ; and the hghtest form in the South. 



Sphenodon punctatum was the form so elaborately described by Dr. 

 Gimther. The other species has not been anatomically examined. 

 Classijication 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 Eeptilia : — 



I. Sqaamata. II. Loucata. III. Cataphracta. 

 He divides the Squamata into Ophidia, LacertiUa, Pihynchocephalia. If 

 external characters alone were considered, he says it would most resemble 

 AyamidcB, of which genus Professor Peters thinks it merely an aberrant form. 

 Professor Seeley talks of Lacertia, Ehynchocejjhalia, and Crocodilia. In his 

 " Forms of Life," Eolleston talks of it as a " low lizard." 



Huxley divides the LacertiUa 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 mth amphicoelous and those with procoelous 

 vertebrae — Kionocrania amphiccelous and Kionocrania procelor. Those with 

 amxDhicoelous vertebrae are again divided into Acrodont or Pleurodont, and 

 Thecodont. There are three Orders : Acrodont or Pleurodont Acalabota, 

 Rhynchocephalia, and Homeosauria. 



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 aUied 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 LacertiUa 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., Ehynchosaurus 

 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 Archegosaiirus, stegocephalic batra- 



* " Student's Elements of Geology," 349. 



