HOMALOCRANIUM. 145 
Fam. COLUBRIDZ GLYPHODONTES. 
HOMALOCRANIUM. 
Homalocranion, Dum. Mém. Ae. Se. xxiii. p- 490 (1853). 
Tantilia, Baird & Gir. Cat. N.-Amer. Rept. p. 182 (1853). 
Lioninia, Hallowell, Proc. Ac. N. Se. Phil. 1861, p. 484. 
Microdromus, Giinth. Ann. & Mag. N. H. 1872, ix. p. 17. 
Synopsis of the Central-American species *. 
I. Seven upper labial shields. 
A. Two nasal shields. 
a. Scales in thirteen series. 
1. miniatum. 
6. Scales in fifteen series. 
a. The first pair of lower labial shields in contact with each other. 
2. atriceps ; (3. melanocephalum) ; 4. gani; 5. boulengeri; 6. bocourti ; 7. armillatum ; 
8. breve ; 9. michoacanense ; 10. annulatum. . 
8. The median lower labial shield is in contact with the anterior chin-shields. 
ll. deppii; 12. teniatum; 13. mestum; 14. schistosum; 15. reticulatum; 16. canulum. 
B. One nasal shield. 
17. mexicanum; 18. virgatum. 
II. Six upper labial shields. 
19. bimaculatum; 20. rubrum. 
* The following species are recorded from Texas, and in all probability occur south of the Rio Grande. I 
introduce them here for purposes of comparison with their allies :— 
Homalocranium planiceps. 
Coluber planiceps, Blainv. Nouv, Ann. Mus. Hist. Nat. iv. p. 294, t. 27. fig. 3 (1835). 
Homalocranion planiceps, Dum. & Bibr. Erpét. vii. p. 857; Jan, Iconogr. Ophid. xv. t. 2. fig. 2; Bocourt, 
Miss. Sc. Mex., Rept. p. 581, t. 36. figg. 7, ‘7 a—d. 
Hab. Nort America, Texas, Duval Co. (W. Taylor), California (Botta). 
Head rather narrow, depressed. Eye small, not quite one third the length of the snout. Vertical shield 
rather broad, with an obtuse angle in front and an acute one behind. Seven upper labials; posterior nasal 
scarcely in contact with the anteocular; one ante- and two postoculars; temporals 1+1. The first pair of 
lower labials form a suture together. Scales in fifteen rows, without apical groove. Ventrals 153, 134 
(Blainville), 140 (Bocourt) ; subcaudals 45. Upper parts light olive, each scale with a brownish dot at the 
base, lower parts white; head black above, the black extending over some portion of the middle of the neck. 
This species was hitherto known from a single specimen only in the Paris Museum. The specimen in the 
British Museum is 10 inches long, of which the tail takes 13. 
Although Jan’s and Bocourt’s accounts are taken from the same specimen, the type in the Paris Museum, 
they do not agree in important details. Jan figures the first pair of lower labials as distinctly separate ; 
BIOL. CENTR.-AMER., Rept., January 1895. *19 
