188 DR. A. GUNTHER ON SIAMESE REPTILES. [April 23, 



This and the following species belong to the genus Acanthosaura, 

 as defined by Dr. Gray (Catal. Liz. p. 240). The tympanum is di- 

 stinct ; a short spine between it and the dorsal crest, which is rather 

 low. No femoral or prseanal pores. A short spine behind the orbital 

 edge, and separated from it by a deep notch. Back and sides co- 

 vered with small, smooth scales, slightly turned towards the dorsal 

 line, and intermixed with scattered larger ones, which are keeled ; 

 belly and legs with larger, keeled scales. Tail slightly compressed 

 at the base, the rest being round and without crest ; all its scales 

 are keeled, those on the lower side being oblong and provided with 

 more prominent keels. Throat without cross-fold and without dis- 

 tinct longitudinal pouch ; a slight oblique fold before the shoulder. 



3. Acanthosaura capra. 



The upper orbital edge not serrated, terminating posteriorly in a 

 long moveable horn ; no spine above the tympanum or on the side of 

 the neck. Nuchal crest high, not continuous with the dorsal crest, 

 which is rather elevated anteriorly. Crown and cheek without mark- 

 ings. 



The tympanum is distinct ; no femoral or prseanal pores. Back 

 and sides covered with small, smooth scales, which become gradually 

 larger and more distinctly keeled towards the belly ; no large scales 

 intermixed with the small ones, only a few appear to be a little 

 larger than the rest. Tail slightly compressed at the base, surrounded 

 by rings of oblong, keeled scales. Throat expansible ; a very slight 

 fold before the shoulder. 



4. DiLOPHYRUS MENTAGER. 



Dorsal crest not interrupted above the shoulder, interrupted above 

 the hip ; caudal crest as high as that on the back ; no large scales 

 on the side of the neck ; sides of the throat with large convex or 

 tubercular scales. 



This species belongs to the genus Dihphyrvs, Gray (Catal. Liz. 

 p. 238). A high crest, composed of sabre-shaped shields, extends 

 from the nape of the neck to the second fifth of the length of the 

 tail, being interrupted above the hip. Scales on the back and the 

 sides of equal size, very small, with an obscure keel obliquely directed 

 upwards ; those on the belly smooth, on the lower side of the tail 

 rather elongate, strongly keeled. Tympanum distinct. Throat with 

 a cross-fold. Orbital edges and sides of the neck without spines. 

 Tail transversely banded with black. 



One stuffed specimen is 30 inches long, the tail taking 21. 



5. Tropidophorus microlepis. 



Snout rather narrow and produced. Scales on the back strongly 

 keeled, the keels not terminating in elevated spines. Back of the 

 tail with two series of moderately elevated spines, the series not being 

 continuous with those on the back of the trunk. Scales of the throat 

 smooth, or very indistinctly keeled. Tail with a series of plates 

 below, which are much larger and broader than the scales of the 



