356 LOWER VERTEBRATES. 



and small reptiles — is much more abundant at evening, or during the early morning, 

 than under the enormous heat of a nearly vertical sun. 



We now come to those ophidians, Pythonidje, which, because of their great size, 

 have been known from the time of the earliest writers. Though of dimensions large 

 enough to satisfy the cravings of the ordinary searcher after the marvellous, they have 

 nevertheless been the subject for most exaggerated stories, and it is extremely diffi- 

 cult to find data which have not been more or less subject to the influence of imagina- 

 tion. The ancient writers were especially fond of magnifying the powers of these 

 serpents. Valerius Maximus writes : "And since we are on the subject of uncom- 

 mon phenomena, we may here mention the serpent so eloquently and accurately 

 recorded by Livy ; who says, that near the river Bagrada, in Africa, a snake was seen 

 of so enormous a magnitude as to prevent the army of Attilius Regulus from the use 

 of the river; and after snatching up several soldiers with its enormous mouth, and 

 devouring them, and killing several more by striking and squeezing them with the 

 spires of its tail, was at length destroj-ed by assailing it with all the force of military 

 engines and showers of stones, after it had withstood the attack of their spears and 

 darts : that it was regarded by the whole army as a more formidable enemy than even 

 Carthage itself; and that the whole adjacent region being tainted with the pestilential 

 effluvia proceeding from its remains, and the waters with its blood, the Roman army 

 was obliged to remove its station : he also adds, that the skin of the monster, measur- 

 ing 120 feet in length, was sent to Rome as a trophy." Krefft, alluding to this piece 

 of remarkable history, says ; " Snakes 10 to 14 feet long are considered very large now- 

 a-days, and in former ages may have kept armies at bay, but our better acquaintance 

 with their habits enables us to treat them with the contempt they deserve." 



Not only has the size of these animals been exaggerated, but their swallowing 

 powers have, in some works, appeared as almost unlimited. The animals on which 

 the pythons ordinarily feed are seldom larger than a small dog, and though they may 

 seize and overpower animals as large as a goat, to swallow them " horns and all " is 

 absolutely impossible. 



The Pythonidse, in general structure as well as in their habits, resemble the BoseidsB, 

 though they are all Old World forms, and have some of the labials deeply pitted, a 

 characteristic which at once determines them. There are skeletal characters also 

 which can be made use of in identification. In the boas the frontal bones are broader 

 than long, while the opposite holds for the jiythons. The rock-snakes, or Pythonidas, 

 inhabit tropical Asia, Africa, and Australia, and though accounts are not rare of their 

 attaining the fabulous length of forty feet, specimens by actual measurement very 

 rarely reach one half that length. The body is rounded ; tail prehensile ; head de- 

 pressed and rounded in front ; eyes of moderate size, the elliptical pupil having its 

 longer diameter vertical ; scales smooth, subcaudals in two rows ; some of the labials 

 are pitted ; teeth on the intermaxillary, maxillary, palatine, pterygoid and mandibulary 

 bones and none grooved ; and the adults are provided with rudimentary hind limbs, 

 placed each side of the vent, and called ' spurs,' These organs are supposed by the 

 natives to be used in fighting, though they probably have sexual functions, or may be of 

 use in grasping the limbs of trees as the animal swings over the surface of the water. 

 Pythons generally prefer those localities which border on some quiet pool, where they 

 lie in wait, either suspended from an overhanging limb, or hid in the luxurious vege- 

 tation of the ground, or possibly partly submerged in the water, waiting the arrival 

 of some small animal, which, as it is about to drink, the reptile seizes by the snout, 



