128 



A 2^ATURALIST IN MEXICO. 



dome of Popocatepetl, piercing the clouds; through the 

 center of the town flowed the little, nameless river, flowing 

 through a beautiful gorge bordered by luxuriant vegetation. 

 All about us were old volcanic cones, the only green and 

 fertile spot to be seen being the town of Yautepec We 

 could see that the lava streams which flowed from Popo- 

 catepetl on the southeast were very large, and must have 

 reached nearly, or quite, to the Gulf. The small cones 

 about the base of the plateau looked broken and jagged, as 

 though a tremendous explosion had taken place. 



Molluscan life was here quite abundant, and I was for- 

 tunate enough to discover a new species of PotamopyrguSy 



\vhich Mr. H. A Pilsbry 

 has called P. Bakeri in 

 honor of its discoverer. 

 It was found in the little 

 river which runs through 

 the town. Such forms 

 as Pupa servilis, P Con- 

 tractu, Stenopus elegans, 

 Planorbis pa?'vus, and 

 Physa oscula7is were 

 quite numerous. Birds 

 were not numerous. 



POTAMOPYKGUS BAKERI, PILSBKY. 



The town was built upon Cretaceous limestone, and 

 several mountain ridges could be seen to the southwest. 

 The whole plateau, and the numerous small cones in the 

 neighborhood, seemed to have been thrust up through this 

 deposit. At the bridge crossing the river a curious fact 

 was observed; the rock on the left bank was composed o^ 

 limestone, while that on the opposite side was composed 

 of lava, the river flowing between the two deposits. 



At night we had a concert of .frogs, which made most 



