OPHIDIA. 453 



the Tortoises are really terrestrial animals, and are strictly 

 vegetable feeders. The most familiar species is the Testudo 

 Gr&ca, which is indigenous in Spain, Italy, and Greece. A 

 much larger species is the Indian Tortoise (Testudo Indicd), 

 which attains a length of over three feet. 



DISTRIBUTION OF CHELONIA IN TIME. The earliest-known 

 traces of Chelonians occur in the Permian rocks, in the lower 

 portion, that is, of the New Red Sandstone of older geologists. 

 These traces, however, are not wholly satisfactory, since they 

 consist solely of the footprints of the animal upon the ripple- 

 marked surfaces of the sandstone. Of this nature is the Chelich- 

 nits Duncani, described by Sir William Jardine in his classical 

 work on the " Ichnology " of Annanciale in Dumfriesshire. The 

 earliest unequivocal remains of Cheloniida are in the Oolitic 

 rocks (the Chelone planiceps of the Portland Stone). Fossil 

 Ckdoniida, Emydidce, and Trionycida occur, also, from the 

 Upper Oolites to the present day, the Eocene period being 

 peculiarly rich in their remains. In the Tertiary deposits of 

 India (Siwalik Hills) there occurs a gigantic fossil Tortoise 

 the Colossochelys Atlas which is believed to have been eighteen 

 to twenty feet in length, and to have possibly survived to 

 within the human period. 



ORDER II. OPHIDIA. The second order of Reptiles is 

 that of the Ophidia, comprising the Snakes and Serpents, and 

 distinguished by the following characters : 



The body is always more or less elongated, cylindrical, and 

 worm-like, and whilst possessing a covering of homy scales, is 

 always unprovided with a bony exoskelton. The dorsal ver- 

 tebrae are concave in front (proccelous), with rudimentary trans- 

 verse processes. There is never any sternum, nor pectoral 

 arch, nor fore-limbs, nor sacrum, and as a rule there are no 

 traces of hind-limbs. Rudimentary hind-limbs, however, are 

 occasionally present (e.g., in Python and Tortrix). There are 

 always numerous ribs. The two halves or rami of the lower 

 jaw are composed of several pieces, and the rami are united 

 anteriorly by ligaments and muscles only, and not by cartilage 

 or suture. The lower jaw further articulates with the skull by 

 means of a quadrate bone (fig. 192, a\ which is always more 

 or less movable, and is in turn united with the squamous por- 

 tion of the temporal bone (" mastoid bone "), which is also 

 movable, and is not firmly united with the skull. The superior 

 maxillae are united with the praeraaxillse by ligaments and 

 muscles only, and the palatine arches are movable and armed 

 with pointed recurved teeth. Hooked conical teeth are always 

 present, but they are never lodged in distinct sockets or alveoli. 



