178 [October, 



Remarks. In Tropidinotas taxis pilotus the bars upon the back are much wider 

 apart than in the above species, and it has but two posterior ocular plates ; the 

 arrangement of the temporal plates is also different ; the frontal plate is much 

 larger, and it has thirty-one rows of scales. Tropidonotus taxis pilotus is remark- 

 able for its great size, being perhaps larger than any of our known water serpents ; 

 transversus is a much smaller animal. The markings upon the back and sides 

 correspond in some degree with Say's description of Coluber calligaster, but 

 the scales in C. calligaster are smooth. The latter animal is most probably the 

 one well know as Col. eximius. 



Phrynosoma planiceps. 



Sp. Char. Head more compressed, longer and broader than in P. cornutum ; 

 nostrils within the supraciliary ridge; upper jaw bordered posteriorly by a row 

 of pointed spines ; central spine of the croiarn separated from the two adjacent 

 spines by a wide interval ; front part of head furrowed in the centre ; scales of 

 chin of nearly equal size ; abdominal scales smooth or indistinctly carinated ; 

 tail longer than in cornutum, and less suddenly tapering to a point; ground 

 color of animal light yellow or ash color ; (brown mingled with yellow in 

 cornutum.) 



Dimensions. Length of head 9 lines ; greatest vertical measurement 7 lines; 

 breadth posteriorly, inclading spines, 1 inch 2 lines ; length of body to vent 

 3 inches ; length of tail 1 inch 7 lines ; length of humerus 7 lines ; of fore arm 

 6J ; of hand to extremity of longest finger, including nail, 7| lines; length of 

 thigh 9 lines ; of tibia 9 lines ; of foot to extremity of longest toe nail 9^ lines ; 

 total length 5 inches 4 lines. 



Habitat. Western Texas, near the Rio Grande. 



SCELOPORUS MARMORATUS. 



Sp. Char. Four plates behind the rostral and between the nostrils, the two 

 first more or less linear ; six plates upon the frontal region ; behind these, five 

 plates surrounding one which is pentagonal; posterior to these, midway between 

 the supraciliary ridges, a single large hexagonal plate (intraorbital ;) snout 

 rather pointed, more narrow than in delicaiissimus; body slender; scales bi- 

 punctate posteriorly. 



Dimensions. Length of head 6^ lines ; greatest breadth 4 lines ; length of 

 neck and body to vent 1 inch 5 lines ; length of tail 2 inches 10^ lines ; length 

 of humerus 3 lines ; of fore arm 3 lines ; length of hand to extremity of longest 

 finger 4 lines ; length of thigh 5 lines ; of tibia 5 lines ; of foot to extremity of 

 longest toe 7 lines : circumference of body 14 lines ; total length 4 inches 10 

 lines. 



Habitat. San Antonio, Texas. 



SCELOPORUS DELICAIISSIMUS. 



Sp. Char. Four plates behind the rostral and between the nostrils ; the two 

 first much smaller than the latter; nine plates upon the frontal region, in two 

 rows (four in front and five posteriorly ;) behind these five plates without the 

 central pentagonal one above described; snout somewhat obtuse; body more 

 slender than that of marmoratus ; scales bipunctate posteriorly. 



Dimensions. Length of head 6 lines; greatest breadth 4 lines; length of neck 

 and body to vent 1 inch 5 lines ; length of tail 3 inches 2 lines ; length of hu- 

 merus 3 lines ; of fore arm 3 lines ; of hand to extremity of longest finger 4 

 lines ; of thigh 4 lines ; of tibia 6 lines ; of foot to extremity of longest toe 

 11 lines ; total length 5 inches 1 line. 



Habitat. San Antonio, Texas. 



PSAMMOPHIS FLAVI-GDLARIS. 



Sp, Char. Head long, superior and inferior marginal outline of cranial portion 

 slightly convex ; temples depressed ; body robust ; color light brown or fuscous 

 above ; chin, throat, abdomen, and under part of tail yellow ; 17 rows of scales ; 

 abdominal scuta 130; sub-caudal 97, 



