il8 SYNOPSES AND DESCRIPTIONS. 



between suborbitals and labials. Series of scales 23 — 25, outer two smooth. 

 Ventrals 137 to 1.54—166+21—31. 



A pair of oval dark-brown spots on the occiput. An elongate spot on 

 each side of these from the supraciliary above the hinder labials. A bar 

 from each internasal through the eye to the angle of the mouth. A bar 

 from the eye to the labials. A light line across the head on the supracil- 

 iaries. A pair of large elongate spots on the neck between the hinder 

 extremities of the bars from the supraciliaries. Body with three series 

 of spots on each side, upper two more or less confluent; the upper is larger 

 and darker, and has somewhat the appearance of a medial series that has 

 been divided by a vertebral line. Infralabials with three or four spots 

 on each side. Belly irregularly spotted with brown, darker backward. 

 Mexico. 



(Sistruriis.) 



Ceotalus catena tus, ])I. /A', Jiff. 2. 



Crotalinus catenatus Haf., 1818, Am. Month. Uoi/., IV, 41. 



Larger than C. miliarms, with which it agrees in plan of coloration, except 

 in the possession of a dorsal band of red, which, however, is not always 

 present in that species. It is readily distinguished by a large anteorbital 

 in contact with the nasal and prefrontal, a small subtriangular loreal, which 

 does not reach the prefrontal, and a greater number of dorsal rows and of 

 ventral scutes. Rostral high, with seven sides, all concave. Nasals large. 

 Loreal small, subtriangular, acute-angled between the anteorbital and nasal. 

 Anteorbitals two; upper large, much longer than the lower, bent upward 

 to meet the prefrontal, in contact with the nasal ; lower narrow. Sub and 

 postorbitals 3 — 5. One to five small scales in front of the pit. The large 

 suborbital in contact with the fourth and fifth labials. Labials 11 — 14. 

 Scales in 23 — 25 rows, one to three of the outer smooth. Ventrals 136 — ■ 

 153+20—29. Spots in the dorsal row, 35—48. 



Varies from light ashy brown to black on the back. Beneath the range 

 is from yellowish, spotted or punctulate with olivaceous, to dark olive or 

 slaty brown, flecked with lighter. In cases the spots on the flank are sepa- 

 rated by very narrow lines of light color. Specimens from the more ex- 

 posed prairies ai'e apt to be ashy and faded above and very dark beneath. 

 Seven series of spots, dorsal large and more or less emarginate in front and 



