298 CLASS xv. 



b) Tail compressed, carinate above (Polydadalus WAGL., Hydrosaurus 

 ejusd.) 



Sp. Varanus niloticus DUM. and BIBR., Lacerta nilotica L., Tupinambis 

 ornatus BAUD., Ann. du Mus. n. PI. 48 ; Cov. R. Ani., ed. ill., Rept. PI. 

 10 bis, fig. i ; not in the Nile alone, but in different other rivers of West 

 and South Africa; Varanus Bengalensis DOM. and BIBR., Monitor gem- 

 matus GUERIN Iconogr., Rept. PI. 3, fig. i; Varanus bimttatus, Tupi- 

 nanibis bivittatus KUHL, SCHLEGEL Alb. Tab. 21, Diet. univ. d'Hist. nat., 

 Rept. PI. 4, fig. 2 ; this species, very common in Java and the rest of the 

 Sunda Isles, grows to nearly 8' in length, lives amongst bushes, in low 

 situations ; it swims and dives very well. 



The species of the division of Monitor resemble the order of the serpents, 

 not only in their tongue but also in the long narrow under-jaw, only 

 loosely united in the middle. The covering of scales reminds us of that of 

 Acrochordus and of Hydrophis. 



Family XIX. Iguanoidei. Tongue fleshy, thick, not protrac- 

 tile, with apex alone free, entire or emarginate at the apex. 

 Eyelids distinct, free. Teeth in some connected with the inner 

 margin of jaws, in others fixed upon the free edge (culmen) of jaws. 

 Head mostly covered with scales or small scutella, more rarely 

 scutate. Back or tail often crested. Four feet pentadactylous 

 (posterior very rarely tetradactylous), with toes free, unequal. 



This family, very numerous in species, is especially remarkable 

 from the great diversity of forms, which has occasioned the esta- 

 blishment of a number of genera. Only a single species, which is 

 also common to North- Africa and Asia Minor, occurs in the South- 

 east of Europe ; all the rest are from other quarters of the world, 

 many from Asia, but by far the most from South America. In 

 the American species the teeth are attached to the inside of the 

 jaws (pleurodontes WAGL., prosphyodontes WIEGM.) j in those of the 

 Eastern hemisphere they are (with a single exception) placed on 

 the edge of the jaws and soldered there (acrodontes WAGL., emphyo- 

 dontes WIEGM.). For this observation, more precisely confirmed by 

 WIEGMANN and WAGLER, the science is indebted to the meritorious 

 zoologist KAUP. From this different attachment of the teeth this 

 family may be divided, as has been done by DUMERIL and BIBRON, 

 into two groups, on better grounds than from the presence or the 

 absence of teeth in the palate, as was done by CUVIER. The divi- 

 sion, however, into ground-iguanas or agamas with flat head and 

 flat depressed body, and tree-iguanas with compressed body, as 

 proposed by WIEGMANN, appears to be more natural. Consequently 



