41. SONORA 863 
195. Sonora semiannulata Baird & Girard 
BicoLor GROUND SNAKE 
Plate 96 
Sonora semiannulata Bairp & Girarp, Cat. N. Amer. Rept., Pt. 1, 
Serpents, 1853, p. 117 (type locality, Sonora, Mexico); Barrp, 
Rep. Pac. R. R. Surv., Vol. X, Pt. III, 1859, p. 15, pl. XX XIII, 
fig. 88; Barro, U. S. Mex. Bound. Surv., Vol. II, 1859, Rept., p. 
21, pl. 19, fig. 3; Cope, Bull. U. S. Nat. Mus., No. 1, 1875, p. 36; 
Yarrow, Bull. U. S. Nat. Mus., No. 24, 1883, p. 87; Van Den- 
BURGH & S.evin, Proc. Cal. Acad. Sci., Ser. 4, Vol. 3, p. 411; VAN 
DensurcuH & Stevin, Proc. Cal. Acad. Sci., Ser. 4, Vol. 5, No. 4, 
1915, p. 100; STEJNEGER & Barsour, Check List N. Amer. Amph. 
Rept., 1917, p. 92; Van DenBurcH & Stevin, Proc. Cal. Acad. 
Sci., Ser. 4, Vol. XI, 1921, pp. 29, 38. 
Contia semiannulata Garman, Mem. Mus. Compr. Zool., Vol. VIII, No. 
3, 1883, pp. 90, 164. 
Contia isozona Corr, Proc. Acad. Nat. Sci. Phila., 1866, p. 304 (type 
locality, Arizona); Corr, Bull, U. S. Nat. Mus., No. 1, 1875, 
p- 36; Yarrow, Surv. W. rooth Merid., Vol. V, 1875, p. 537, pl. 
18, fig. 1; Garman, Mem. Mus. Compr. Zool., Cambr., Vol. VIII, 
No. 3, 1883, pp. 92, 164; BouLenGcer, Cat. Snakes Brit. Mus., 
Vol. II, 1894, p. 266. 
Contia episcopa isozona Corr, Bull. U. S. Nat. Mus., No. 17, 1880, p. 
21; Yarrow, Bull. U. S. Nat. Mus., No. 24, 1883, p. 87; Cope, 
Proc. U. S. Nat. Mus., Vol. XIV, 1892, p. 601; Brown, Proc. 
Acad. Nat. Sci. Phila., 1901, p. 67; Brown, Proc. Acad. Nat. Sci. 
Phila., 1903, p. 553; Dirmars, Reptile Book, 1907, p. 331; STRECKER, 
Baylor Bulletin, Vol. XVIII, No. 4, 1915, p. 37. 
Chionactis episcopus isozonus Cope, Report U. S. Nat. Mus. for 1898, 
1900, p. 939, fig. 239; Branson, Kansas Univ. Sci. Bull., Vol. II, 
No. 13, 1904, p. 416, fig. 34; Batty, N. Amer. Fauna, No. 25, 
1905, pp. 35, 47; Exvtis & Henperson, Univ. Colorado Studies, 
Vol.2X;No. 25 1913,.p. Ir. 
Chionactis isozonus RicHarpson, Proc. U. S. Nat. Mus., Vol. 48, 1915, 
p- 426. 
Description —Head but little wider than neck, rather 
flat-topped, temporal regions not much swollen. Snout 
rounded, not greatly depressed, not pointed in profile, pro- 
