542 REPORT OF NATIONAL MUSEUM, 1898. 



Each of these genera includes but one species, excepting Xantusia, 

 which embraces two. All belong to the Pacitic and Sonoran districts, 

 except Lepidophymai which occurs in the Central American (Mexican). 



In addition to the characters which I have previously given, Mr. 

 Boulenger states' that the sternum is without fontanelle. I find the 

 hyoid apparatus has characters somewhat similar to those of the 

 LacertidiB. The ceratohyals and second ceratobranchials are both 

 present and there is a well developed free epibranchial. Its proximal 

 end overlaps the distal end of the second ceratobranchial. It passes 

 around the extremity of the first ceratobranchial and extends forward. 

 In Lepidophyma it has the jjeculiarity, which I have not seen in any 

 other lizard, of being inserted on the lateral process of the basioccipital. 

 In Xantusia riversiana it terminates before reaching this point. In 

 Lepidophyma it displays a concave expansion as it passes the extremity 

 of the first ceratobranchial, in which lies the helicoid cartilaginous 

 extremity of the latter. In neither genus are the hypohyals prolonged 

 with the ceratohyals, as in Anguidse, nor beyond them as in the Teiidie. 



The stapedial disk in Lepidophyma is not sunk in a canal, as in the 

 Iguanidse and some other Sauria. The columella is slender, and termi- 

 nates in the interstapedial cartilage. This supports an oblique carti- 

 laginous rod, one end of which (suprastapedial) is attached to the 

 osseous wall above, and the other longer one (epistapedial) is in contact 

 by a flat surface of its extremity with the membranum tympani. 



The remarkable characters of the skull in Xantusia are described 

 under the head of that genus. Bocourt^ represents a i)robably similar 

 structure in Lepidophyma. 



Xantusia and Jjepidophyma agree in their visceral characters. The 

 corpus adiposum is small and projects freely into the abdominal cavity. 

 The alimentary canal is distinguished into stomach, small intestines, 

 and rectum only, the latter elongate. The posterior border of the liver 

 has a small middle lobe; right lobe moderately produced. Lungs equal. 

 Mesenteries normal. 



The contents of the stomach of a Xantusia riversiana include vege- 

 table remains, and fragments of hymenopterous and coleopterous 

 insects, showing a mixed diet. 



XANTUSIA Baird. 



Xantusia Baird, Proc. Acad. Nat. Sci. Pbila., 1858, p. 255.— Copk, Proo. Acad. 

 Nat. Sci. Phila., 1883, p. 29; Americau Naturalist, 1895, p. 758.— BouLENtJKK, 

 I Cat. Liz. Brit. Mus., 1885, II, p. 327. 



Body cylindric, without crests or spines. Tail cylindric, moderate. 

 Head covered with large polygonal plates; superciliary scales seg- 

 mental; belly with square plates in transverse series. Tail encircled 

 by whorls of quadrate scales. Femoral pores present, pierced in an 



' Cat. Liz. Brit. Mus., II, 1885, p. 325. 



2 Mission Scientiiitiue de Mexiqne, pi. xx C4, fig. 2. 



