Vol. 70.] THROUGH THE ANDES OF PERU AND BOLIVIA. •>1 



Pig. 4. Leptoccelia acutiplicata (Conrad), Devonian; Coniri, Bolivia. (See 

 p. 39.) 



5. Euphemus cf. indicus Waagen, Upper Carboniferous ; San Pedro, 



peninsula of Copacabana, Bolivia. (See p. 36.) 



6. Producttis semireticulatus Mart., Upper Carboniferous ; Yampu- 



pata, peninsula of Copacabana, Bolivia. (See p. 34.) 



7. Posidonomya escuttiana, sp. nov., Oxfordian ; Morro de Arica, 



Chile. (See p. 9.) 



Plate IX. 



(All the figures are of the natural size.) 



Pigs. 1 a-1 c. Spirifev condor D'Orb., Upper Carboniferous ; Yarbichambi, 

 Bolivia. (See p. 32.) 



Plate X. 



Pig. 1. Geological section through the Andes, from Arica (Chile) to the 

 Bolivian ' Yungas.' Scales : — Horizontal, 1 : 500,000 ; vertical, 

 1 : 100,000. 

 2. Sketch-map of the country between Arica on the Pacific coast of Chile 

 and the Bolivian ' Yungas,' on the scale of 1 : 1,000,000. 



Discussion. 



The President (Dr. A. Strahan) desired to remind the Meeting 

 •of the great obligation under which they, as geologists, had been 

 placed by the liberality of Mr. W. E. Balston. Mr. Balston had 

 not only defrayed the cost of the expedition, but had been fortunate 

 in Ins choice of so competent a geologist. The Fellows had heard 

 an able account of the geology of an inhospitable region, and had 

 had the opportunity of examining an admirable collection of speci- 

 mens ; but they had not been told of the great personal risk and 

 ■extreme hardships under which the work had been carried out. 



Prof. Sollas remarked that Mr. Balston, knowing that new 

 railways were in course of construction in Peru, had conceived the 

 happy idea of sending out an expedition to rescue for Science such 

 organic remains as might be revealed in the railway-cuttings, and 

 of applying the information which these cuttings afforded to the 

 interpretation of the structure of the country. The Author had 

 been invited to undertake the work on Mr. Balston's behalf, and 

 had laboured enthusiastically for two years at the task, which was 

 one that demanded no common powers for its accomplishment. It 

 had not been his good fortune to discover new and strange forms 

 of life ; but he had made the best use of his opportunities, and had 

 thrown additional light on the structure of one of the most 

 interesting regions in the world, already rendered famous by the 

 studies of such distinguished observers as A. d'Orbigny and David 

 Forbes. 



Dr. J. W. Eyans remarked that the Author had two great 

 advantages over his predecessors just mentioned, whose route he had 

 followed. He had had the benefit of the sections exposed by the 



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