Amphibians and Keptiles of Mexico. 317 



over the surface of tlie water like a spider also fails to convey an 

 accurate idea of the method of progression throiigh tlie water. 



An examination of the storaachs of a niimber of specimens re- 

 veals principally insects. A few blades of grass, flakes of bark and 

 seeds are also present, but in such small quantities as to Warrant 

 the conclusion that they were picked up accidently. This harmonizes 

 with the observations of Ditmars ^j on captive specimens, but not 

 with Boülengee's -) Statement that the genus is herbivorous. 



Iffnana igiiana rhinolopha (Wiegmann). 



Very common along the streams between the Arroyo Negra and 

 the San Juan River. It was not observed at Lake Catemaco, and 

 we could find uo natives who had seen it thei-e. 



As was to be expected the specimens obtained are referable to 

 the variety. all of them having the spines on the snout. The number 

 of spines on the neck and body in ten individuals varies from 47 

 to 56, the average number being 51. 



The Iguana is preeminently a riparion species in the region 

 studied. With the exception of a few young specimens it Avas not 

 observed elsewhere than on the immediate banks of the streams or 

 along the deep water lagoons on the flood plains. Young individuals 

 were occasionally observed several hundred yards from the water on 

 the river flood plains. and in one instance a young one was observed 

 a hundred yards from a shallow pond on the prairie and several 

 miles from a large body of water. The form is also preeminently 

 arboreal, its favorite haunt being the limbs of trees that overhang 

 the water. When first alarmed they endeavor to escape Observation 

 by becoming quiet, and they are then to be observed only with 

 great difficult}^ This is due partly to the fact that the green pre- 

 dominating in the coloration harmonizes with the foliage and partly 

 to the counter-shading. The counter-shading is slight, but very 

 eifective. The writer has often. at a distance of five or ten feet, 

 closely examined bushes containing several iguanas before seeing 

 one (generally revealed by a slight movement), and then observed 

 the inconspiciousness to be in great part due to the fact that the 

 delicate counter-shading destroyed all evidence of thickness, the 

 animal appearing as if cut out of card board. When further alarmed 



1) Reptile« of the World, p. 133, New York. 



2) Catalogue of Lizards in the British Museum, Vol. 2, p. 3. 



