144 Transactions of the Society. 



Madagascar, whilst living examples survive in the Mauritius, 

 Bourbon, and many other small islands of the Indian Ocean, and on 

 Galapagos Island. 



Gigantic marine turtles with extremely degenerate shells, like 

 the modern leathery turtle, occur fossil in the Eocene of Europe 

 and of America, and living in the West Indies. One living sub- 

 order of Chelonia, the Pleuroclira, is confined to the Southern 

 Hemisphere, although its fossil remains have been discovered in 

 Europe and North America. The genus Miolania has been found 

 in the Pleistocene deposits of Queensland, and has also been obtained 

 from Lord Howe Island, 400 miles distant from the Australian 

 coast. Quite recently Dr. Moreno has obtained the same genus 

 (only specifically distinct) in the Tertiary deposits of Argentina, 

 South America. 



The Ichthyopterygia, or fish-limbed reptiles, make their first 

 appearance in the Trias, range throughout the Mesozoic, with little 

 structural modification, and disappear in the Chalk. In outward 

 form they must have closely resembled the Cetacean mammals of 

 the present day, such as the dolphin, with its large head, long 

 rostrum, numerous and uniform teeth, and no apparent neck. 

 Their hind limbs have never (unlike the Cetacea) quite disappeared, 

 although sometimes extremely reduced in size ; and the caudal fin 

 was expanded in a vertical plane, as in fishes, not in a horizontal 

 plane, as in the Cetacea. It is possible that the Ichthyopterygia 

 were originally derived from land animals, as the earliest Triassic 

 forms show a slightly elongated character in the radius and ulna, 

 and the teeth are in less uniform series than those from the Jurassic 

 and Cretaceous rocks — but we know nothing of their terrestrial 

 ancestors. The vertical folding of the walls of the conical teeth is 

 only paralleled by that observed in many Labyrinthodonts ; their 

 short biconcave vertebral centra may also best be compared with 

 Mastodonsaurus. 



Another remarkable group of Beptiles having its origin in the 

 Trias, called the Khynchocephalia (beak-headed), in allusion to the 

 typical beak-shaped rostrum of several of the genera, has a single 

 representative at the present day in the small lizard-like Sphenodon 

 or Hatteria, found on certain small islands off New Zealand. The 

 two best known genera in the Permian are Palceohatteria, a long- 

 tailed-lizard-like reptile of small size, and Protorosaurus, a large 

 reptile from the Upper Permian ; but the British form of Hypcro- 

 dapedon Gordoni from the Trias of Elgin, and a larger species 

 from the Trias of Central India, with Rhynchosaurus from the 

 Trias of Shropshire, and another form from Bavaria, make up a 

 most remarkable and all but extinct group. 



The Squamata, or Scaled Animals, represented by the Lizards 

 and Snakes, are, comparatively speaking, of recent origin, only 

 going back to the Cretaceous period ; one of the earliest of these 



