596 CHORD AT A. 



Sub Order II. TRIONYCHIA. Fresh-water forms with poorly ossified 

 carapace, but ribs and vertebrae connected with it. Our leather turtles. 

 (Amyda*) and soft- shelled turtles (Aspidonectes*)ot savage habits belong 

 here. 



Sub Order III. CRYPTODIRA. Carapace well developed and united 

 with ribs and vertebrae, but the pelvic arch free. The species are numer- 

 ous, including terrestrial, fresh-water, and marine forms. CHELYDRID^, 

 fresh water, tail long. Chelydra serpentina, * snapping turtle ; Machrochelys 



FIG. &24. Eretmochelys imbricata, tortoise-shell turtle. (From Hajek.) 



lacerti?ia,* alligator turtle. CHELONID^E, marine, paddle-like feet. Tha- 

 lassoclielys caretta,* loggerhead; Chelone my das* green turtle, the favorite 

 of epicures; Eretmoclielys imbricata, whose horny shields furnish tortoise 

 shell. TESTUDINID.E, terrestrial, including Xerobates* the ' gopher turtle * 

 of the South, the giant Testudoot the Galapagos Islands, and the enormous 

 fossil Colossochelys atlas of India, 18-20 feet long, 8 feet high. Other 

 families contain our mud turtles (Kinosternon *), box turtles (Cistudo*), 

 and terrapins (Malaclemmys*). 



Sub Order IV. PLEURODIRA. Pelvis united to carapace and plastron. 

 All belong to the southern hemisphere. 



Order V. Rhynchocephalia. 



These resemble the lizards not only in body form (four five- 

 toed feet) and in scaly skin, but in certain anatomical matters as 

 well: lack of hard palate, presence of epipterygoid, transverse 

 cloacal opening, and heart, lungs, and brain. On the other hand 

 they recall the crocodiles in having two postorbital arches and 

 immovable quadrate. The large abdominal sternum and abdominal 

 ribs are noticeable as well as the uncinate processes of the true 

 ribs. The notochord is but incompletely replaced. The group 

 appears in the Permian and is thus one of the oldest of reptilian 

 types, and is usually regarded as ancestral to all the orders yet to 

 be mentioned. The only living species, Sphenodon (Hatteria) 

 punctata, belongs to the New Zealand region. 



Order VI. Dinosauria. 



This order included some of the largest land animals which have ever 

 existed. Some of them were from forty to one hundred feet long and 

 twelve to twenty feet high (Amphiccelias, Camarasaurus). In some there 



