472 REPORT OF NATIONAL MUSEUM, 1898. 



separate sac of the " peritoueum." They occupy the usual position out- 

 side of tbe peritoneum, and as they do not project freely into the body 

 cavity, can not be «iaid to occupy separate sacs. In lizards where tbey 

 do project into the crelom they do occupy iiouches of peritoneum. 

 Beddard^ does not regard the ventral i^eritoneum as such, but thiuks 

 it to be distinct from it, calling it the " horizontal membrane." But it 

 has all the relations of the ventral peritoneum of other lizards, and I 

 believe it to be truly such. It is very loosely attached to the muscular 

 walls by connective tissue. 



In Varanns salvator the hemipenis is furnished with transverse 

 flounces, which are longitudinally ribbed, except at the thin edge. The 

 folds form a chevron directed distad. Apex smooth. In V. arenarius 

 the apex is smooth, and on the base are longitudinal series of acute 

 papillte. In V. grisctis the organ is entirely smooth in a specimen 

 examined, but I do not know whether this condition is normal. 



Boulenger remarks of the Varanidae as follows: 



Tongue smooth, A'ery long and slender, bifid, retractile into a sheath at the base. 

 Teeth large, dilated at the base, which is fixed to the inner side of the jaws. Pal- 

 ate toothless. Premaxillary single, narrowed, and much prolonged posteriorly; 

 nasal bones coalesced and narrow; two frontals; a single parietal; a supraorbital 

 bone ; postorbital arch incomplete ; a bony supratemporal arch ; pterygoids and pala- 

 tines widely separated; infraorbital fossa bounded by the pterygoid, palatine, and 

 transvtirse bone, the maxillary being exchided. 



The characters of the genus Varanus are as follows : 



No dermal cranial ossifications; head covered with small polygonal scales. Eyelids 

 well developed; ear-opening distinct. Limbs well developed; clavicle slender; 

 interclavicle anchor-shaped. Dorsal scales roundish, juxtaposed, surrounded by 

 rings of minute granules; ventral scales squarish, arranged in cross rows. No 

 femoral or preanal pores. Tongue sheathed at base. Tail very long. A single 

 genus confined to the Old World and Australia, and forming a perfectly isolated 

 group I 'araniis Merrem 



In the mandible, Meckel's cartilage is not overroofed by the spleuial 

 bone. The dentary is not produced far posteriorly on the external side. 

 The surangular bone is distinct. The symphysis mandible is not 

 closely fitted, but is more or less free. 



The genus Varanus includes, according to Boulenger, 28 species. 

 None of these are of small size, and some of them reach a length of 

 6 feet. 



HELODERMATOIDEA. 



Helodtrmatoidea Gill, Smithsonian Report fur 1885, 188G, p. 800. 



Petrosal bone produced anterior to anterior semicircular canal. Olfac- 

 tory lobes uutlerarched by frontal bones. Supratemporal arch want- 

 ing. Clavicle proximally simple. Vertebrfe prOcojlous. Tongue 

 papillose. 



This superfamily embraces but one family, the American Heloderma- 



' Proc. Zo(d. Soc. Lond., 1888, p. 89. 



