406 SPECIAL GEOLOGY. 



small conical nasal horn; the fossil horn here depicted (fig. 

 286.) has been referred to the iguanodon, and is supposed 

 to have occupied a similar position on the nasal bones. 



Several bones belonging to the extremities of this saurian 

 have been found in Sandown and Brook Bays, Isle of 

 Wight; one femur measures 40 inches (fig. 199); another 

 attains the colossal dimensions of 4 feet in length. 



Professor Owen* dissents from the opinion that the 

 iguanodon attained the length estimated from a comparison 

 made between the bones of the iguana and that extinct 

 reptile, and thinks that the relative proportions between 

 the size of the bones in these genera is a premises not to be 

 relied on, and suggests that the land reptiles of the wealden 

 might have had limbs much longer in proportion to their 

 length than the iguana of our epoch. The discovery of the 

 Maidstone iguanodon, which comprises a larger portion of 

 the skeleton than had previously been found, has served to 

 confirm several important particulars relative to the general 

 structure of the genus. This specimen was discovered in 

 the lower greensand, which proves that the existence of this 

 reptile was protracted till an early period of the chalk, as the 

 remains of crocodiles and alligators are now borne by tropical 

 rivers to the ocean ; so these remains might have been floated 

 by a river into the cretaceous sea. 



THE HTL^OSATJEUS f was discovered in the strata of 

 Tilgate forest. The peculiarity of this saurian consists in 

 the large angular spinous bones which lie embedded with 

 the skeleton. Many existing iguanas, as Iguana cornuta, 

 have a fringe of cartilaginous spines, extending from the 

 neck to the tail. In this extinct reptile the appendage is 

 supposed to have been of bone, and to have been inserted in 

 like manner along the back. Bones have been found in 

 the Hastings sand which are referred to pterodactyles, and 

 numerous large vertebrae from the wealden beds belong to a 

 new genus, the Cetiosaurus, which is supposed to have had 

 an alliance with the cetacean type of structure. 



The Eev. P. B. Brodie discovered in the wealden of the 

 Yale of AYardour, in Wiltshire, many genera of insects 



* Report on British Fossil Reptiles, 

 t 'TAcuos (hylceos), a wood ; aavpos (sauros), a reptile. 



