MUSEUM OF COMPARATIVE ZOOLOGY. 283 



Squier reports having seen a specimen of coal said to have come from 

 Lake Titicaca. 



It is rather surprising that as yet no Subcarboniferous has been 

 found, though the Devonian was found by Mr. Agassiz close alongside 

 of the Coal Measures, the island of Coati being only two or three miles 

 distant from Titicaca.* Very extensive beds in Bolivia have been 

 referred to the Devonian by d'Orbigny and Forbes, but as yet the 

 palaiontological evidence is quite defective. Salter states that of the 

 fossils referred by d'Orbigny to the Devonian, only two are certainly 

 supra-Silurian, and those are as likely to be Carboniferous as Devonian. 

 Of the fossils referred to the Devonian by Salter only one, Phacops 

 latifrons, was considered as undoubtedly of that age, and this loses 

 much of its value in being in a rolled pebble from an uncertain locality. 



The following notes explain in a general way the structure of the 

 Carboniferous system of the elevated plateau of Peru (A. Agassiz) : — 



In addition to the fossils described already by Professor Derby a 

 number of Fusilinse were also found in the Carboniferous beds of 

 Lake Titicaca. They have been sent to Mr. Brady for identification. 

 The Carboniferous beds from which the fossils above noticed are 

 derived form the southern terminus of the Carboniferous system as 

 marked on the map of Bolivia and Peru by David Forbes. But this 

 system is not limited to the comparatively small area assigned to it 

 by Forbes. It consists, for the whole area which I have examined, of 

 a series of rather limited elongated basins, the longitudinal axis 

 extending, as noticed by Forbes, in a general northwestern to south- 

 eastern direction. The strata generally form a series of short folds 

 often quite sharp, so that at comparatively small distances the rocks 

 dip in very different directions. In the Straits of Tiquina, as men- 

 tioned by Forbes, we have strata thrown up nearly vertically dipping 

 east on the west side, and west on the east side ; it is by a series of 

 such faults more or less prominent, that the successive basins of the 

 Carboniferous system of the elevated plateau of Peru have been sepa- 

 rated. Near Copacabana the metamorphic rocks underlying the 

 denuded sandstones dipping to the east and west are plainly seen. 

 Another such protruded mass I have observed near Puno. Another 

 forms the hill of dark red trachyte to the west of Juliaca, rising directly 



* See Note on page 282 (A. Agassiz). 



