1S92.] -^11 fCope. 



reeled anteriorly at an acute angle, -svith median pectineal angle. Ischia 

 directed vertically downwards, with angulus tubei-osus, and pre- and post- 

 ischiadic acuminate cartilages. 



It is remarkable that in the large species of the allied genus Tupinambis 

 the proscapular process is wanting. 



Xaxtusiid^. 



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

 lenger states {Catal. Brit. 31>is.) that the sternum is without fontanelle. 

 I find the hyoid apparatus has characters somewhat similar to those of 

 the Lacerlidoe. 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 

 round the extremity of the first ceratobranchial and extends forwards. 

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

 lizard, of being inserted on the lateral process of the basioccipilal. In 

 Xontusia riversiana (Plate vi. Fig. 41) 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 cartilag- 

 inous extremity of the latter. In neither genus are the hypohyals pro- 

 longed with the ceratohyals, as in Anguidte, nor bej^ond them as in the 

 Tiid:T. 



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

 uanidte and some other Lacertilia. The columella is slender, and termi- 

 nates in the interstapedial cariilage. This supports an oblique cartilaginous 

 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 sur- 

 face of its extremity with the membranum tympani (Plate v, Fig. 26). 



The remarkable characters of the skull in Xantusia are described under 

 the head of that genus. Bocourt (Jlission Sci. de Mea-iqiie, PL xxg, Fig. 

 2), represents a probably similar structure in Lepidophyma. 



Xa:nttjsia Baird. 



My knowledge of the osteology of this genus is derived from the X 

 riversiana, specimens of which I owe to my friend. Dr. J. J. Rivers, of 

 Oakland, Cal. 



The OS premaxillare has an elongate spine above and a nearly transverse 

 posterior border below. Xasals well developed, distinct. Frontal single, 

 grooved below. Parietal single, without pineal foramen, produced poste- 

 riorly so as to overhang the occipital bone and foramen magnum ; being 

 connected with the former by a median keel which it sends downwards. 

 The supraoccipital is subhorizontal and is not articulated in the usual 

 way with the paiietal, having only the median contact above mentioned. 

 It is coossified with the exoccipitals. The prefrontal is small and is not 

 produced far over the orbit. Lachrymal absent. Jugal with the super- 



