SYNOrSES AND DESCRIPTIONS. 25 



the dark color is produced tow.u-d the throat. On account of the amount 

 of A^ariation of this species in dift'erent localities, it is hardly to l)e separated 

 fn iiu tlie prcM-eding. Canada to Central America. 

 liirtaJis. K..\vs 19. Si)()ts 70— ?)(). Ventrals 140— 165 +60—8;-) pairs. 



Mississipjti Valley and eastward. 

 marcidiiiis. Rows 21. JSjHjts 50 — 75. A\>ntrals 145 — 175f50 — 00 pairs. 



Texas to Mexico. 

 pnrietalis. Rows 21. Spots 70— 110. Ventrals 160— 185 f 50— 90 pairs. 



Valley of the Missouri and westward. 

 mfernalis. Rows 17—19. Spots 100—120. Ventrals 145-1754-75-95 



pairs. California and northward. 

 collaris. Rows 19. Ventrals 151 — 165 f 58— 84 (Jan.) Mexico to Panama. 

 ord'mafus. Agrees with sirfali.'i, but has the lower series of spots more 



distinct, while the stripes are almost obsolete, and is found in va.rious 



isolated localities of the same district, as Alabama, South Carolina, 



Martha's Vineyard, and Nova Scotia. 



TROriDOXOTUS SIPEDON, j>/. //, Jiff. 3. 



Coluber sipedon Limu', 1758, Syst. Nat., cd. X, 21i). 

 Tropidonotus sipedon Holbrook, 1842, N. A. Horp. IV, p. 6, pJ. 29. 



Stout, fusiform, Ix'lly brond; head distinct, narrow forward; tail smaller 

 than the body, tapel-ing. Eye medium, pupil round. Mouth-cleft deep, 

 abruptly curved near tlie angle. Nine head-shields. Rostral low, broader 

 than high. Nasal in two parts, nostril betAveen. A loreal. One anteor- 

 bital, sometimes two. Postorbitals two to four. Temporals 1+2, large. 

 Labials 8 (7 — 9), sixth and seventh large. Infralabials 10 (9 — 11), tifth 

 and sixth large. Submentals two pairs, large, not in contact with the 

 mental. Scales strongly keeled, in 23 to 25 roAvs, dorsal narroAv, outer 

 broader than long, keeled to smooth. Ventrals 130 — 155. Anal divided. 

 Subcaudals 40 — 75 pairs. 



Varying from ashy to very dark broAvn, or to broAvnish-red ; Avith three 

 series of dark-edged brown sjjots; dorsal about ten scales in Avidth, varA'ing 

 in shape from irregular rounded to nearly square, distinct or confluent Avith 

 the lateral into transverse bands, Avhich Aviden toAvard the A'ertebral roAvs. 

 There are usually tAventy-five to thirty spots on the tlank, Avider than long, 

 and from fifteen to tAventy on the tail. Commonly the spots on the flanks 

 are more or less opposed and confluent anteriorly, but posteriorly alter- 



