14 REPTILES AND BIRDS. 



insects, small terrestrial or aquatic molluscs; others, such as 

 Ophidians and Crocodiles, attack Birds, and even Mammals. Large 

 Serpents, owing to the distensibility of their oesophagus, frequently 

 swallow animals broader than themselves at the moment of seizing 

 their prey. 



Reptiles, whether Batrachians, Ophidians, or Chelonians, are 

 mostly oviparous, sometimes ovo-viviparous, and generally very prolific. 

 The eggs of some are covered with a calcareous envelope, as in the 

 turtle. Sometimes they are soft, and analogous to the spawn of fish, 

 as in the Batrachians. Most species do not hatch their eggs by sitting 

 upon them, but bury them in the sand, trusting to the heat of the 

 sun, which hatches them in due course. To this the Pythons form a 

 partial exception. Batrachians content themselves with diffusing their 

 spawn or eggs in marshy waters or ponds, or they bear them on their 

 backs until the time of hatching approaches. On leaving the egg 

 young Tortoises have to provide immediately for their own wants, for 

 the parents are not present to bring them nourishment or to defend 

 them against enemies. Parental affection, so manifest among the 

 superior animals, does not exist in oviparous species, except in those 

 that hatch their eggs in the body of the mother. The young are 

 consequently, so to speak, produced in a living state, and fully pre- 

 pared for the battle of life. The loves of these animals present none 

 of that character of mutual affection and tender sympathy which dis- 

 tinguishes the Mammalia and Birds.* When they have ensured the 

 perpetuity of their species, they separate, and betake themselves again 

 to their solitary existence. 



Some Reptiles attain dimensions truly extraordinary, which render 

 them most formidable. Turtles are met with which weigh as much 

 as i, 600 pounds; and carapaces have been found that measured as 

 much as six feet in length. Although the average length of the 

 Crocodile is about eight to nine feet, they have been seen twenty- 

 four and even thirty feet long. 



In Chelonians the surface of the skull is continuous without 

 movable articulations. The head is oval in the Land Tortoises, the 

 interval between the eyes large and convex, the opening of the 

 nostrils large, the orbits round. The general distinguishing character- 

 istic of Tortoises is the external position of the bones of the thorax, 

 at once enveloping with a cuirass or buckler the muscular portion of 

 the frame, and protecting the pelvis and shoulder bones. The ribs 



* Birds, however, are ovipirous, and nevertheless manifest the strongest 

 parental affection. — Ed. 



