22. SIAGONODON 625 
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 Barrp & Girarp, 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; SteynecER, N. Amer. Fauna, No. 7, 1893, p. 203; Van Den- 
BURGH, Proc. Cal. Acad. Sci., Ser. 2, Vol. 5, 1895, p. 136. 
Stenostoma humile Peters, Monatsberichte Akad. Wiss. Berlin. 18573 
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. 1, 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; Betpinc, West Amer. Scientist, Vol. III, No. 
24, 1887, p. 98. 
Stagonodon dugesii Bocourt, Miss. Sci. au Mex., Rept., 1882, p. 507, 
pl. XXIX, fig. 9 (type locality, Colima, Mexico). 
Glauconia humilis BouLencEerR, Cat. Snakes Brit. Mus., Vol. I, 1893, 
p- 70; Cope, Amer. Naturalist, Vol. XXX, 1897, p. 1014; Mocquarp, 
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; Dirmars, Reptile Book, 
1907, p. 210, pl. LXIII. 
Siagonodon humilis Van Densurcu, Occas. Papers Cal. Acad. Sci., V, 
1897, p. 150; McLaty, Contributions to Neotropical Herpetology, 
1899, p. 3; VAN Densurcu, Proc. Cal. Acad. Sci., Ser. 4, Vol. 3, 
1912, p. 153; Van DenspurcH & S tevin, Proc. Cal. Acad. Sci., 
Ser. 4, Vol. 3, 1913, p. 409; VAN Densurcu & Stevin, Proc. Cal. 
Acad. Sci., Ser. 4, Vol. 4, 1914, p. 145; STEJNEGER & Barsour, 
Check List N. Amer. Rept., 1917, p. 72; STEPHENS, Copeia, No. 
54, 1918, p. 34; VAN Densurcu & Sievin, Proc. Cal. Acad. Sci., 
