EXTINCT SCALED REPTILES. 249 



without provocation, leaping towards him from a considerable distance when he 

 approaches. I met, in the course of my daily rambles through the woods, many 

 jararacas, and once or twice very narrowly escaped treading on them, but never 

 saw them attempt to spring. On some subjects the testimony of the natives of a 

 wild country is utterly worthless. The bite of the jararacas is generally fatal." 



Extinct Groups of Scaled Keptiles. 



A brief reference may be made to two groups of extinct reptiles from the 

 rocks of the Secondary epoch, which must be included in the order Squamata. 



Long-Necked The first of these groups is represented by a small snake-lizard, from 

 Lizards. ^q English Chalk, described under the name of Dolichosaurus, and 

 forming a suborder (Dolichosauria) by itself. Whereas ordinary lizards have not 

 more than nine vertebrae in the neck, this strange reptile has upwards of from 

 fifteen to seventeen, while its hind-limbs are characterised by having the whole of 

 the five metatarsal bones of the foot well developed, and its whole structure 

 reveals a very generalised type of organisation. The vertebrae have additional 

 articulations like those of snakes. It is probable that these reptiles form the 

 ancestral group from which the other suborders of scaled reptiles have originated. 

 Cretaceous A still more remarkable group of the order is formed by certain 



Sea-serpents, carnivorous marine reptiles from the Cretaceous rocks, many of which 

 attained gigantic dimensions, and may not inappropriately be designated extinct 

 sea-serpents. Commonly known as Mosasauroids, on account of the first described 

 genus (Mosasaurus), having been found on the banks of the Meuse, they form a 

 suborder technically known as the Pythonomorpha. They all had a much elon- 

 gated body, and a skull approximating in structure to that of the monitors among 

 existing lizards, the nasal and premaxillary bones being welded together, and the 

 quadrate very loosely attached to the skull. Teeth were present on some of the 

 bones of the palate, as well as on the margin of the jaws; those of the latter series 

 being large, sharply pointed, and attached by expanded bases. The bones of the 

 shoulder-girdle and pelvis were more or less imperfectly developed ; and the limbs 

 were modified into paddles or flippers, with the toes enclosed in a common skin, 

 and devoid of claws. There were either nine or ten vertebrae in the neck ; and 

 whereas, in some cases, the vertebrae resembled those of snakes, in other instances 

 they lacked the additional articulations distinguishing the latter. It will be un- 

 necessary to particularise the various genera of these reptiles, but it may be 

 mentioned that while some of the better-known forms have been described as 

 Mosasaurus, others have received the names of Liodon and Clidastes. They appear 

 to have inhabited the Cretaceous seas of all parts of the world, having been 

 obtained from regions as far apart as England, New Zealand, and Argentina ; and 

 while some attained a length of between 25 and 30 feet, others were not more 

 than 8 or 10. Then, again, while in some cases the jaws were armed with power- 

 ful teeth to their extremities, other forms had a long, toothless beak. 



