1852.] 



125 



of the Journal, of late Nos. of the Proceedings, and of previous Nos. 

 of the same, deficient in the series of that Society. 



August 24:th. 

 Prof. Haldeman in the Chair. 



Letters were read 



From Lieut. W. S. Boyd, U. S. Marine Corps, dated Valparaiso, 

 June 27th, 1852, referring to a collection of shells now offered for sale 

 by Mr. Weld, Purser U. S. N. 



From Prof. Ehrlich, dated Linez, April 3, 1 852, presenting the works 

 announced this evening. 



From M. Laporte, Sr., dated Bordeaux, May 4, 1852, in reference 

 to an exchange of foreign insects for those of this country. 



August 31s^. 

 Mr. Ord, President, in the Chair. 



The Committee on the following paper by Prof. Baird and Mr. Chas. 

 Girard, reported in favor of publication in the Proceedings. 



Characteristics of some New Reptiles in the Museum of the Smithsonian 



Institution, 



By Spencer F. Baird and Charles Girard. 



SECOND PART, 



Containing the species of the Saurian order, collected by John H. Clark, under 

 Col. J. D. Graham, head of the Scientific Corps U. S. and Mexican Boundary 

 Conamission, and a few others from the same or adjoining territories, obtained 

 from other sources, and mentioned under their special headings. 



Holbrookia texana, B. and G. Cophosaurus texanusy Trosch. Arch, fiir 

 Naturg. for 1850, (published in 1852,) 389. Tab. VI. 



This species, easily distinguished from H. maculatay attains a larger size and 

 is provided with a more elongated tail. The body above and the lower surface 

 of the head are grayish, maculated with small yellowish white subcircular dots ; 

 on the upper surface of the tail and hind legs there are transverse bands of black. 

 On the posterior half of the abdomen there are two black crescents, the convexity 

 of which is posterior, and extending from near the back to the belly, without 

 coming into contact either above or below. The space between the crescents, 

 as well as an anterior and posterior area, are yellowish white on the back and 

 blue on the belly. The breast, the medial line of the belly, the inferior surface 

 of thighs and tail, are unicolor, of a uniform yellowish white; the tail underneath 

 presents seven or more large subquadrangular or subcircular black patches. In 

 the female, the abdominal crescents are represented by two lateral spots. 



Localities. Along the Rio San Pedro, a tributary of the Rio Grande del Norte. 



Holbrookia affinis, B. and G. This species comes nearest to H. texana^ 

 from which however it can be readily distinguished by its more slender form and 

 its proportionally larger dorsal scales and superciliary plates. The coloration 

 differs but little from the former in the female, to which sex the only specimen 

 in our possession belongs. The back however is darker, scattered with black 

 spots, of which two dorsal rows may be followed from the occiput to the base of 

 the tail, where they meet and constitute a crescent or an angle, the convexity of 



20 



