1905.] AMPHIBIANS AND REPTILES. 201 



which lies at an altitude of about 7600 feet, was fruitless. In the 

 month of September 1904, however, when we revisited this 

 district, I was able to ascertain that these Newts live regularly in 

 the stream below Contreras (altitude 8090 feet) down to about 

 7900 feet, where the stream leaves the hills, and runs, still 

 swiftly, in its stony bed through the Pedregal, or recent field of 

 lava, then through rich evergreen meadows into Lake Xochimilco. 

 Moreover, I can now add with certainty that A. cdtamirani is 

 absolutely aquatic throughout its life. The natives (millers, field- 

 labourers, and boys) knew the creatures well. They called them 

 " axolotes sordos " (deaf, having no ears), and described them as 

 axolotes sin aletas (without winglets, meaning gills) ; when I 

 searched for them on land, on the bordering meadows, under 

 stones, or amongst the trees, the people laughed at my ignorance 

 of expecting to find "fishes" on dry land. There are no fishes in 

 that stream. But this, their " fish," they pronounced as no good, 

 because these axolotes de cerro (Mountain Axolotl) are not eaten 

 like the " axolotes del lago." 



During our last visit the mountain-streams were transformed 

 into turbid roaring torrents, and it was only at a few spots that 

 the Newts were visible, generally in some stiller water, in the 

 shelter of some great boulder. There they stood, or rather were 

 lying, on little patches of sandy bottom, the larvse working their 

 gills vigorously, the adult motionless except for the undulating 

 tail, and never rising to the surface to breathe. They were all 

 extremely shy, quickly hiding beneath or between the stones. 



In the Montes de las Cruzes, close to the railway-station Dos 

 Bios, the streams form here and there little swamps or ditches, 

 with much watercress in the slowly-flowing water ; there we 

 found plenty of larvee ; the adult only in the running water. 

 Not one of these mountain-streams runs dry. 



The lungs are well developed. 



The only specimen, a larya 100 mm. long, which I succeeded in 

 bringing home alive in 1902, metamorphosed within 8 weeks, 

 losing the fins and gills, and closing the gill- openings completely, 

 but it died before losing the yellow and black piebald coloration. 



The distribution of Amhlystoona in Mexico coincides absolutely 

 with the large central and western portion of the country, which 

 has been covered with volcanic masses, i"epeatedly or successively, 

 since the Eocene epoch ; and the last outburst, which produced the 

 Pedregal near Mexico, is known to have occurred after this part of 

 the country was already inhabited by man. It was impossible for 

 Amphibia to live on such a terrain until it was weathered enough 

 to sustain a pei'manent and moisture-loving vegetation. In fact 

 every locality where A. tigrinum is known to occur is on the 

 Quaternary, mostly sandy, patches formed by the disintegrating 

 debris of the volcanic masses ; or it is found in the lakes, all of 

 which are partially filled-up moxnitain valleys. 



"We have to conclude that the Amblystomas are recent 

 immigrants from the North. Where they have met such lakes, 



