NATURAL SCIENCES OF PHILADELPHIA. 191 



labials from the occipital. Superior labials seven, or six from confluence of 

 two, sometimes of the third and fourth which bound the orbit. Inferior 

 labials seven, fourth largest ; postgeneial equal pregeneial, separated by 

 scales. Vertical shield longer than broad, outlines straight, posterior angle 

 less than right ; occipitals nearly as long as from their border to rostrals, 

 emarginate behind. Gastrosteges 126, 11 urosteges forty pair. Color olive 

 brown (one specimen light brown), with dense, minute punctulations above 

 and below, and about fifty-four light-edged black cross-bars extending over 

 six rows of scales, alternating with shorter ones on the sides : both are 

 broken into spots on the neck, whore there is a large postoccipital blotch on 

 each side 



Length of rictus of mouth, 4 lines ; of head and body, 10 inches, 9 lines ; 

 of tail, 2 inches, 8 lines. 



Habitat. Mexican plateau between the eastern range and the valley of 

 Mexico. Sent by our correspondent, Dr. Ch. Sartorius. 



Ancistrodon bilineatus, Gthr. Ann. Mag. N. H. 1863, 364. 



Fine specimens in Mus. Smithsonian from Western Mexico, from Guadal- 

 axara and Colima, from our correspondents, I. I. Major and Jno. Xantus. The 

 species nearest our A. contortrix. 



Crotalus r a v u s. 



Twenty-three rows of scales, all keeled, except the exterior ; keels of the 

 median thick. Head broad in front, canthus rostralis and muzzle rounded, 

 the latter elevated. Rostral abruptly acuminate ; both pairs of fiontals 

 broader than long ; occipitals well developed, their outer portion cut off 

 wholly or in part by a suture. Temporal scales all smooth. Pit separated 

 from labials by a series of small scales ; one row between the former and 

 orbit. Superior labials eleven and twelve, last eight nearly equal ; in- 

 feriors, twelve and thirteen ; gastrosteges, 147, urosteges, 26. Color yel- 

 lowish brown, with from twenty-six to thirty-one elongate deep brown 

 narrow parallelogramic spots, four scales long to five wide, and a series 

 of as many short transverse bars on the sides opposite them : a series of 

 thrice the number of small spots on the inferior rows of scales. Belly yel- 

 lowish, thickly varied with blackish brown. Tail yellow brown, with but 

 two proxrmal cross-bars. Head pale, similar, without spots or marks, except 

 a minute punctulation. A brown anteriorly furcate nuohal spot. 



Length of rictus, 5.7 lines; of head and body, 7 inches, 6 lines: of tail, 

 10.2 lines. 



Hub. Table land of Mexico. 



The specimens in the Mus. Smithsonian are young : the species is, no 

 doubt, small, and nearer C. miliarius than any other. 



Caudisona polysticta. 



The species which I call by this name reminds, at first sight, of the 

 Bothriechis mexicanus, and the head markings resemble those Of the 

 South American Trigonocephalus alternatus. The pattern of color is, how- 

 ever, more broken than in either, and represents a new type in the genus. 



The superciliary plates are normal ; the rostral higher than broad, acu- 

 minate ; two marginals between them, the anterior pair linear , separated by a 

 small plate, the posterior broad oval, separated by two rather narrow plates. 

 Three between the superciliaries, the outer large. Two nasals, two loreals, 

 one above the other. Superior labials fourteen, separated from the orbit by 

 two rows of smooth scales ; inferior labials thirteen ; temporals smooth. 

 Rows of scales twenty-seven, all keeled, except the outer two. Gastrostega 

 123, urostega 19, the first only divided. Crepitaculum slender, acuminate, 

 delicate for the size of the animal; joints eleven. The color above is later- 

 ally gray brown, medially yellowish brown, marked by seven longitudinal 

 1865.] 



