HERPETOLOGY. 



LESSON I. 



GENERAL CHARACTERS. Form. Skeleton. Motion. Nerr.out 

 System. Senses. Nutrition. Apparatus oj Digestion. 

 Blood. Respiration. Lungs Temperature. Secretion. 

 Eygs. Classification. 



CLASS OF REPTILES. 



1. That part of Natural History which treats of Reptiles, is 

 termed Herpetology, from the Greek, erpctun, a creeping thing, 

 a reptile, and logos, a discourse. 



2. The CLASS OP REPTILES comprises those oviparous verte- 

 brate animals that have cold blood, an aerial respiration, and an 

 incomplete circulation. They have lungs like mammals and 

 birds; but their circulatory apparatus is always so arranged 

 that a part of the venous blood mingles with the arterial, without 

 having passed through the respiratory organ, and in general, 

 this mixture takes place in the heart, which has a single ventricle, 

 into which both auricles open. 



3. In their general form, reptiles bear a closer resemblance to 

 mammals than to birds ; but in this respect they vary very much. 

 The head is almost always small, and the body much elongated, 

 (Plate \,.fig. l } 6, nnd 7.); sometimes they are entirely without 

 extremities, or only possess vestiges of them ; but most of these 

 animals have four paws, formed for walking or swimming. 

 Ordinarily, their extremities are too short to prevent the body 

 from dragging on the ground, and, instead of being parallel to 

 the axis of the body and moving in this direction, they generally 

 stand out from the side and move from without inwards, perpen- 

 dicularly to the axis of the body, an arrangement very unfavour- 

 able to locomotion ; most reptiles seem to creep rather than walk, 

 from which circumstance they derive their name. 



1. What is Herpetology ? . 



2. What, are the general characters of those animals that are comprised 

 in the Class of Reptiles? 



3. What class of anirn ils do Reptiles more closely resemble in their genera! 

 form ? What is the position of their extremities? From wh;it circumstance 

 do they derive their name? 



