TACHYMEXIS CHILE N SIS. 173 



GENUS TACHYMEXIS, WIEGM. 



GEN. CHAR. Body subcylindrical, of moderate length ; tail short, sub- 

 conical, tapering. Head colubrine, slightly detached from the body. 

 Cephalic plates normal. Eyes of medium size. One or two ante- 

 orbitals and two postorbitals. One loral. Two nasals, with nostril 

 between them. Jaws subequal. Dorsal scales smooth. Preanal 

 scutella divided. Subcaudal scutellae disposed upon a double series. 



STN. Tachymeni*, WIEGM. in Nov. Act. Xat. Cur. XVII, I, 1835, 251. GKD. in 

 Gillfss, U. .S. X. Astr. Exped. to S. Hemisph. II, 1855, 213. 



OBSERV. The genus Tacliymeriis, so far, is composed of two species, 

 one from Peru, figured and described by Wiegmann in the work cited 

 above, and another from Chile, described below. 



TACHYMEXIS CHILEXSIS, Grd. 



SPEC. CHAR. Two anteorbital plates. Third and fourth labials con. 

 stituting the inferior rim of the orbit. Dorsal scales disposed upon 

 nineteen longitudinal series. Color olivaceous-brown above, with 

 four longitudinal bands of black, sometimes interrupted along the 

 dorsal region. Beneath yellowish, with the anterior margin of the 

 scutellae black. 



STN. Coronella chiknsis, SCHLEG. Ess. Phjs. Serp. I, 1837, 136, et II, 1837, 70. 

 GUICH. in Gay, Hist, de Chile, II, 1848, 79, PI. iv, fig. 1. 



Dipsas chilensis, DUM. & BIBR. Erpet. gen. VII, u, 1854, 1159. 



Tuchymenis chilensis, GRD. in Proc. Acad. Xat. Sci. Philad. VII, 1854, 226; and 

 in Gillt'ts, U. S. Astr. Exp. to S. Hemisph. II, 1855, 213, PI. xxxvii, figs. 1-6. 



DKSCR. The head is subovoid, being depressed upon its upper sur- 

 face ; the snout is rounded, and the jaws subequal. The cleft of the 

 mouth ascends posteriorly. The eyes, subcircular in shape, are of but 

 moderate development, their diameter being equal to the width of the 

 vertex plate, upon the middle of its length. The vertex plate itself 

 is elongated, subpentagonal, diminishing gradually in width posteriorly, 

 where it is rounded off. The occipitals are about the length of the ver- 



