214 DR. H. GAOow ON MEXICAN [June 6, 



the Isthmus of Tehuantepec, and are restricted to Central 

 America. 



Some species have a very wide, others a very limited dis- 

 tribution. The majority combine humivagous with climbing 

 habits, and show gi-eat adaptiveness to the nature of their 

 surroundings ; for instance, S. sccdaris and S. census do not climb 

 the trees beneath Avhich they live, but prefer the grassy ground, 

 and they are equally at home in the moist, clouded pine-forests 

 and on the more barren, grassy and lava-strewn slopes up to the 

 snow-line. S. variabilis prefers the wooded lowlands of the 

 Atlantic side, and likewise does not climb, loving the banks of 

 rivulets and well-herbed ravines. Others, e. g. >S'. torqitatus, are 

 found only on rocks, stone walls, and buildings ; they are swift. 

 Some — and these are the most depressed in body — are rather 

 sluggish, e. g. S. S2nnosus, and spend most of their time on the 

 ground between sj>iny gTowth of hedges and low trees, which 

 they ascend a little way, in short rapid jerks, when alarmed. 

 Lastly, S. microlepidotus is truly arboreal, ascending the trees in 

 the morning, with the sun, right into the green toj)s, where they 

 hunt for insects. This species has the greatest possible alti- 

 tiidinal range ; from the. hot country of Southern Oaxaca, only a 

 few hundred feet above the level of the sea, to the upper tree-line 

 of Citlaltepetl, about 13,500 feet elevation. 



Many species are vivijoarous. According to my own observa- 

 tions, the following : acardhinus, ceneus, formosus, microlepidotus, 

 scalaris — all gravid in the months of July to September. 



Iguana rhinolopTius is interesting for various reasons. It is 

 the largest Lizard in Mexico, attaining a total length of about 

 5 feet. Always arboreal and aquatic and truly tropical, it occurs 

 in the whole of Central America, but in Mexico, north of the 

 Isthmus, only in the States of Vera Cruz and Southern Oaxaca, 

 everywhere strictly below the Plateau, and on the Pacific side it 

 has been recorded only from Manzanillo near Colima and near 

 Mazatlan ; undoubtedly also near San Bias and in the lower 

 reaches of the Balsas, but this information I have only from 

 hearsay. I never found it in Guerrero. The creature requires 

 permanent, rather sluggish rivers, or deep pools in the savannahs. 

 They clixaib about in the trees, eating the succulent leaves, which 

 they bolt without much chewing, for instance those of the guava 

 tree. Favourite places for resting are the branches which over- 

 hang the water, into which they plump with a loud splash, 

 sinking at once and remaining at the bottom for many minutes. 

 Whilst the adult are dusky, the young are grass-green and are 

 frequently found in the tall grass at the edge of a pool. They at 

 once take to the water and swim to the bottom, with their legs 

 laid back and propelling themselves, like newts, by rapid undu- 

 lating motions of the tail. The eggs are buried in the soft soil, 

 among the roots of a tree, always near the water, in the month 

 of May; by the end of July they are already hatched. They are 

 known as Guanas or Iguanas. 



Ctenosaura aca')ithura is a common Lizard of the hot and warm 



