2 28 VERTEBRATE ANIMALS OF THE UNITED STATES 



Cn In Florida T. sackeni. 



a2 Scales in 21 rows. 



bi Upper labials 7 ; on the Great Plains T. radix. 



b2 Upper labials 8. 



Ci Labials not dark bordered; western States T. ordinoides. 



C2 Labials dark bordered; southwestern States. 



di Spots 74 to 90 T. hammondi. 



do Spots 50 to 60 T. marcianus. 



T. sirtalis (L.) Common garter snake (Fig. 123). Length 750 mm. ; 

 tail 130 mm.; color very variable, varying from greenish to blackish, 



Fig. 123. — Thamnophis sirtalis {from Cope). 



with 3 yellowish, longitudinal stripes and 2 or 3 series of black spots on 

 each side, both stripes and spots being indistinct in some cases; belly 

 greenish: entire country; our commonest snake. 



Subspecies of T. sirtalis 



T. s. sirtalis (L.) Typical form: eastern and central States; west- 

 ward to Minnesota and Missouri. 



T. s. concinnus (Hallowell) . A series of reddish, vertically elongated 

 spots on each side; ground color black; throat and lips red; belly black: 

 coast region of Oregon, Washington and British Columbia. 



T. s. parietalis (Say). Ground color light brown; belly slate color; 

 a series of vertical red bars on each side: Missouri to the coast of Cali- 

 fornia and northward in Oregon and Washington east of the Sierra 

 Nevadas and Cascades. 



T. butleri (Cope). Length 440 mm.; tail 100 mm.; head very small: 

 Michigan. 



T. sauritus (L.) Ribbon snake. Length 660 mm.; tail 230 mm.; 

 body very slender; stripes bright yellow: eastern States; westward to 

 Michigan and Mississippi. 



