6 



UNITED STATES AND MEXICAN BOUNDARY. 



yellowish. Color dark green above, nearly black towards the median line. Back with small yellowish 

 pots. 



2845. Patos, Coahuila. Lt. Couch. 



17. SCELOPORUS THAYERI, B. & G. 



Sceloporns thayeri, B. & G., Pr. A. N. Sc. VI, Aug. 1852, 127. 

 2896- San Pedro, Texas, J. H. Clark.— 2887. Indianola. J. H. Clark. 



18. SCELOPORUS SCALARIS, Wiegmann. 



Sceloporns scalaris, Wiegm. Herp. Mex. 1834, 52; tab. viii, f. 2. 



2284. Los Nogales, Sonora. Dr. Kennedy. 



19. SCELOPORUS MARMORATUS, Hallow. 



Sceloporns marmoratns, Hallow. Pr. A. N. Sc. VI, Oct. 1852, 118. 

 Scelopor^us delicatissimus, Hallow. Pr. A. N. Sc. VI, Oct. 1852, 178. 



2916. Medina, Texas. J. H. Clark.— 4116. Redmond's Ranch, Texas. J. H. Clark. 



20. SCELOPORUS COUCHII, Baird. 



Sceloporus couchii, Baird, Pr. A. N. Sc. Dec. 1858. 



Sp. Ch. — General appearance of S. marmoratns, Hall. Cephalic plates smooth. Scales very small. 

 About 80 oblique dorsal rows from head to tail. Femoral pores, 25. Color above dark green, with 

 two lateral light stripes, separated by 18 rows of scales. Back with irregular spots. Sides with a 

 white band from groin. An obsolete dark indigo patch on each side the belly, widely separated below- 

 Sides of jaw banded transversely with blue and whitish. A sub-circular indigo patch in front of shoulder, 

 surrounded by light blotches. 



2904. Pesquieria Grande, Mexico. Lt. Couch. — 2739. Santa Caterina, New Leon. Lt. 

 Couch. 



21. EUPHRYNE OBESA, Baird. 



Plate XXVII. 



Euphryne obesus, Baird, Pr. A. N. Sc. Dec. 1858. 



Sp. Ch. — Width of head nearly equal to distance from nose to ear. Tail shorter than the body. General 

 color of the young, olive green, with five broad transverse bars above from head to base of tail, and 

 about as many on the tail; these rings yellow, dotted with red. Beneath, pea green, dotted with black. 

 With increasing age the bands become obsolete and disappear, the general color becoming reddish olive. 



2774 Fort Yuma. Major Thomas.— 4172. Do. A. Schott. 



22. CROTAPHYTUS COLLARIS, Holbrook. 



Agama collaris, Say, Long's Exped. II, 1823, 252. 

 Crotaphytns collaris, Hole. N. Am. Herp. II, 1842, 12: pi. x. 



2694. Sonora. Dr. Kennerly.— 2710. San Antonio to El Paso. J. H. Clark. 



23. CROTAPHYTUS RETICULATUS, Baird. 



Crotaphytns reticulatus, Baird, Pr. A. N. Sc. Dec. 1858. 



Sp. Ch. — Infra-orbital chain in a series of six or eight nearly equal plates. Scales on the gular fold 

 much smaller than those between the fore legs. Above ashy gray, with a hexagonal reticulation of 



