308 PROCEEDINGS OF THE ACADEMY OF 



Caudisona pyrrha sp. nov. 



Scales in twenty-five series, broad and rounded, the two inferior rows 

 smooth. Head short and very obtuse, the nostrils opening subvertically. 

 Superior labials higher than long, three rows of temporals smooth ; scales of 

 vertex small, keeled ; those more anterior, striate. Superciliaries broad oval, 

 striate. Canthus rostralis none. Inferior labials fifteen, the first and second 

 margining a plate which meets its fellow in front of the geneials, and is in 

 other species a continuation of the first. Gastrosteges 178, urosteges 24; 

 joints of rattle 9. The general tint of this species is a bright salmon red, the 

 scales of the inferior rows punctulate with brown. Other details of structure 

 and coloration are given in the description below. 



The species is one of the most handsomely colored of the genus. Its affini- 

 ties are with the C. m i t c h e 1 1 i i m., but it exhibits an even higher degree 

 of subdivision of the head shields. Mus. Smithsonian, No. 6606. 



I am now acquainted with eighteen well defined species of this genus, 

 while one or two named remain to be further investigated. They are dis- 

 tributed as follows : 



Regio Neotropica 5 



S. R. Brasiliana 2 



S. R. Mexicana .' 4 



Regio Nearctica 13 



S. R. Sonoriana 10 



S. R. Californiana 1 



S. R. Media 3 



S. R. Orientalis 2 



18 



The intensity of distribution is then the Region of Lower California, Upper 

 Sonora and Arizona, which has seven peculiar species, and three which enter 

 from the neighboring districts.* 



The scattered nature of the literature of this subject renders a synopsis of 

 the species of this important genus desirable. The genus divides itself into 



two natural sections : 







I. Top of muzzle covered by three pairs of symmetrical shields in contact ; 

 nasals distinct. 



a. Rattle acuminate. 

 C. DUitissA Linn. Scales in twenty-nine rows, four rows scales below or- 

 bit. Yellow, with two brown longitudinal bands on anterior part of body, 

 remainder with black rhombs embracing yellow centres. Surinam and 

 Mexico, to Vera Cruz. 



C. terrifica Laurenti. Four rows scales below orbit ; brown, with two 

 darker bands above anteriorly, and a series of large darker dorsal rhombs 

 with yellow outlines. Brazil, Mexico. 



C. basilisca. Cope. Two and three rows scales below eye ; rows on body 

 29; labials 14. Yellow- brown, with large adjacent chestnut-red, yellow- 

 bordered dorsal rhombs, alternating with chestnut spots ; no longitudinal 

 bands anteriorly. Western Mexico. 



a.*. Rattle parallelogrammic. 



C. molossus Bd. & Gird. Twenty-nine rows of scales, eighteen labials, 

 separated by five rows from orbit. Brownish-sulphur above, with small 

 transverse reddish dorsal rhombs, the angles produced as lateral bands ; no 

 longitudinal bands on neck; tail black. Arizona, New Mexico. 



* These facts have been pointed out, Pioc. Acad. 1S61, 294. 



[Oct. 



