OPHIDIANS. 507 



the TEGUIXIN MONITOR? What very large sp. is found in Guiana? What 

 representative of this family is found in N. A. ? How is it known from the 

 other Lizards ? 



What is the SEVENTH FAMILY ? To which Continent are they confined? 

 Describe the habits of the TRUE LIZARDS. What is said of the gen. Lacerta ? 

 Describe the Eyed-Lizard. The GREEN L. What of the LAND L. ? Of the 

 VIVIPAROUS or SCALY L. ? 



What of the EIGHTH FAMILY ? To what order is this and the succeeding 

 family closely related? How have they been regarded? How are the 

 Chalcides readily distinguished ? What further characters are given ? To 

 what regions are these Reptiles confined ? Are any found in the U. S. ? 

 How many sp. have been described? Name the sub-families into which 

 they have been arranged ? What gen. is found in N. A. ? Why is it 

 called the GLASS-SNAKE ? What sp. in the U. S. ? State particulars in 

 regard to the other gen. and sp. 



What is the NINTH FAMILY? Give the peculiarities of the family? How 

 many sp. ? Name their localities. How many sub-families ? How distin- 

 guished from each other ? Describe the gen. and sp. Name the first sub- 

 family. What is said of the second sub-family ? What of the third ? 



SECTION V. 



THIRD ORDER. OPHIDIANS OR SERPENTS. 

 Ophidia. (Gr. 6'<pt, ophis, a serpent.) 



The Ophidians are particularly distinguished by the total ab- 

 sence of external limbs in a majority of the species, or else the 

 limbs are so rudimentary as to be discoverable only by dissection, 

 or on very close examination : so that, as Cuvier remarks, they 

 are more truly deserving of the name of Reptiles than any other 

 order. 



They possess an elongated form, with which is conjoined not 

 only great flexibility, but amazing strength. Their upper sur. 

 face is covered with narrow and somewhat pointed scales, of 

 small or moderate size, imbricated or disposed like tiles ; these 

 are called squama. The under surface is covered with broad 

 transverse scales or plates, called scuta, of which the hind edge 

 in one overlays the front edge in the other. The top of the head 

 is also usually covered with plates. The whole "of the delicate 

 and pellucid outward membrane which covers the scales, is shed 

 entire, and renewed once a year, or perhaps oftener ; it is some- 

 times called the slough. All serpents pass the winter, or cold- 

 est part of the year, in a torpid state ; when coming out from 

 this state, the skin is cast or exuviated ; it is first detached 



