REPTILES 



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the mouth; scales in 25 to 27 rows; upper labials 14 or 15: the Great 

 Plains from Canada to Texas and the entire country west to the Pacific; 

 common, being frequently seen in prairie dog burrows, on the young of 

 which they feed. 



Subspecies of C. confluenlus 



C. c. confluenlus Say. Body brightly marked with blotches: the 

 Great Plains. 



C. c. lutosus Klauber. Body brightly marked with small blotches 

 anteriorly and with narrow bars posteriorly: the Great Basin region. 



C. c. oregonus Holbrook. Body brightly marked with blotches: the 

 Pacific Coast States. 



C. scutulatus (Kennicott). Body marked with diamonds like 

 C. atrox; light line back of eye as in C. confluenlus; large scales on top 

 of snout: desert regions of southern Arizona and California. 



C. willardi Meek. A small rattler, with brightly marked head; 

 body dull, with white cross lines: southern Arizona. 



C. lepidus (Kennicott). Length 555 mm.; tail 50 mm.; color green- 

 ish with black rings at wide intervals; scales in 23 rows; upper labials 1 2 : 

 along the Mexican border of Texas, New Mexico and Arizona. 



C. triseriatus Wagler. Length 525 mm.; tail 60 mm.; color gray- 

 ish brown, with 2 series of small brown blotches on the back; scales in 

 21 rows: southern Arizona. 



C. tigris Kenn. Length 650 mm. ; tail 50 mm.; color yellowish gray, 

 with indistinct cross bands; scales in 23 or 25 rows; upper labials 13: 

 southern Arizona. 



Order 4. Testudinata. — Turtles. Reptiles in which the body is 

 wide and short, and is enclosed in a shell composed of a dorsal shield, 

 called the carapace, and a ventral shield, the plastron. The shell, in 

 most cases, is formed of large external, epidermal, horny plates (tortoise 

 shell), which overlie internal bony plates. These latter consist, in the 

 carapace, of the flattened ribs and the flattened trunk vertebrae which 

 coalesce with overlying dermal bony plates, and are surrounded on 

 the circumference of the shell by a series of marginal dermal bony plates; 

 in the plastron they consist of exclusively dermal plates, there being 

 no sternum. The carapace and the plastron are more or less firmly 

 united by a wide bridge on each side. 



The head is a very solid and compact structure, and is often covered 

 with scales. The jaws are toothless and are covered by a horny sheath 

 which forms a cutting edge. The Trionychidce are the only turtles 

 which have fleshy lips. The eye has an upper and a lower lid and also a 



