22. SIAGONODON 



row of small scales runs along the top of the head behind 

 the rostal plate. No supraocular plates are present. The 

 preanal plate is not divided. 



A single species represents this genus in California, Ari- 

 zona and Lower California. 



135. Siagonodon humilis (Baird & Girard) 

 Western Worm-Snake 



Rena humilis Baird & Girard, Cat. N. Amer. Reptiles, Pt. I, Serpents, 

 1853, p. 143 (type locality, Valliecitas, Cal.); Cooper, Proc. 

 Cal. Acad. Sci., Vol. IV, 1870, p. 67; Cope, Bull. U. S. Nat. Mus., 

 No. 32, 1887, p. 64; Stejneger, Proc. U. S. Nat. Mus., Vol. XIV, 

 1891, p. 501; Cope, Proc. U. S. Nat. Mus., Vol. XIV, 1892, p. 

 590; Stejnecer, N. Amer. Fauna, No. 7, 1893, p. 203; Van Den- 

 burgh, Proc. Cal. Acad. Sci., Ser. 2, Vol. 5, 1895, p. 136. 



Slenostoma humile Peters, Monatsberichte Akad. Wiss. Berlin. i857> 

 p. 402; Cope, Proc. Acad. Nat. Sci. Phila., 1861, p. 305; Cope, 

 Proc. Acad. Nat. Sci. Phila., 1886, p. 312; Cope, Bull. U. S. Nat. 

 Mus., No. I, 1875, p. 44; Yarrow, Bull. U. S. Nat. Mus., No. 24, 

 1883, p. 142; Garman, Mem. Mus. Compr. Zool. Cambr., Vol. 

 VIII, 1883, p. 130; Belding, West Amer. Scientist, Vol. Ill, No. 

 24, 1887, p. 98. 



Siagonodon dugesii Bocourt, Miss. Sci. au Mex., Rept., 1882, p. 507, 

 pi. XXIX, fig. 9 (type locality, Colima, Mexico). 



Glaucoma humilis Boulenger, Cat. Snakes Brit. Mus., Vol. I, 1893, 

 p. 70; Cope, Amer. Naturalist, Vol. XXX, 1897, p. 1014; Mocq.uard, 

 Nouv. Arch. Mus. Hist. Nat., Ser. 4, Vol. I, 1899, p. 315; Cope, 

 Report U. S. Nat. Mus. for 1898, 1900, p. 719, fig. 144; Brown, 

 Proc. Acad. Nat. Sci. Phila., 1901, p. 14; Ditmars, Reptile Book, 

 1907, p. 210, pi. LXIII. 



Siagonodon humilis Van Denburgh, Occas. Papers Cal. Acad. Sci., V, 

 1897, p. 150; McLain, Contributions to Neotropical Herpetology, 

 1899, p. 3; Van Denburgh, Proc. Cal. Acad. Sci., Ser. 4, Vol. 3, 

 1912, p. 153; Van Denburgh & Slevin, Proc. Cal. Acad. Sci., 

 Ser. 4, Vol. 3, 1913, p. 409; Van Denburgh & Slevin, Proc. Cal. 

 Acad. Sci., Ser. 4, Vol. 4, 1914, p. 145; Stejneger & Barbour, 

 Check List N. Amer. Rept., 1917, p. 72; Stephens, Copeia, No. 

 54, 1918, p. 34; Van Denburgh & Slevin, Proc. Cal. Acad. Sci., 



