1152 REPORT OF NATIONAL MUSEUM, 1898. 



origin is from some genus like Lachesis, which had u scaly head and no 

 rattle. 



I. Toji of muzzle with three pairs of symiuetrical shields in contnct. (Scales in 



29 rows.) 



Longitmliual bands on neck; fonrrows of scales below orbit; yellow with black 

 rhombs embracing yellow centers C. durissiis Linnicus 



Longitudinal bands on neck; four rows of scales below orbit; brown above with 

 darker light-edged rhombs C. terrificus Laurenti 



No longitudinal bands on neck; yellow brown, with large adjacent chestnut-red 

 yellow-bordered dorsal rhombs, alternating with lateral chest- 

 nut spots; labials, 14; two and three scales below eye. 



C. hasiliscii.s Cope. 



No longitudinal bamls on neck; tail black; brownish yellow above, with small 

 transverse reddish dorsal rhombs, the angles produced as 

 lateral bands; hvu scales below eye. 



C. molossus Baird and Girard 



II. Top of muzzle with numerous scales or small plates. Suj)erciliary not produced. 

 A. Nasal plate not separated from rostral. 



a. One or two lorcals. 



/i. Rostral plate higher than wide. 



y. Tail light with black cross-bands. 



Scales of canthus rostralis hirger than those on top of muzzle; 

 dorsal spots large, pale-edged rhombs on a paler ground; no 



neck stripes; scales in 25-29 rows C. adaviantens IJeanvois 



yy. Tail with brown or indistinct bands. Muzzle with tlie nuirginal 

 scales larger than the median; scales in 23-27; three rows of 

 brown dorsal spots, the median large; postocular band pass- 

 ing above canthus oris C. conftucntiia Say. 



Eight smooth longitudinal plates on top of muzzle; two loreals; 

 scales in 27 rows; a postorbital spot; five rows of dorsal spots. 



C.pohjstietus Cope. 

 Six smooth square plates on top of muzzle; one loreal; scales iu 

 23 rows; three rows of dorsal spots, the median large. 



C. iriseriatus Wagler 



Small; internasal and prefontal plates large; nine supralabials; 



a dark-brown baud from eye to angle of mouth; two rows of 



small brown dorsal sjiots G.pricei Van Denburgh 



yyy. Tail uniformly black. Scales of canthus rostralis larger than 

 those of top of muzzle; postocular band passing above mouth 

 angle; angular spots above uniting into double chevroncd 



cross-bands ; scales in 25 rows. . _ ^ C. horridiis Linujeus 



/3fS. Rostral plate as wide .as or wider than high. 



No canthus rostralis; posterior cauthal plate smaller than interna- 

 sals and decurved, replacing a superior loreal; one loreal; 

 dorsal spots indistinct in adult; postocular band striking 



mouth ; tail white, with black rings C, ruber Cope. 



A canthus rostralis; posterior cauthal i>late larger than internasals, 

 not decurved; two loreals; head scales keeled; six rows of 

 body scales smooth on each side; supraorbitals entire; small, 

 well-separated dorsal rhombs on light ground with lateral 

 spots adjacent; postocular band passing above mouth. 



C. enyo Cope. 

 Supraorbitals generally incised or divided by suture; head scales 

 smooth; all body scales keeled; buft", with small, separate, 

 light-brown dorsal rhombs, which become crossbars poste- 

 riorly; no head bands C. tigris Keuuicott 



