part 1] THROUGH THE ANDES OF PERU AND BOLIVIA. 41 



Both the geological structure of the country and the lithological 

 character of the beds are almost sufficient to warrant this conclusion ; 

 hut more convincing proof was fortunately obtained, in the form 

 of palaiontological evidence, a few miles farther north in a little 

 valley known as Viscachani. 



A short distance beyond the lake lies the disused Indian chapel 

 of Santa Isabel, and in the bed of the stream at this point appear 

 beds of red shaly sandstone showing beautiful ripple-marking ; 

 these have a steep dip of about 80° south-south-westwards, and, 

 although their junction with the overlying beds is not visible, they 

 appear to belong to an older series (probably of Devonian age, being 

 very similar to the red shales of Tirapata). 



The valley of Viscachani is flanked on the west by a steep 

 escarpment of grey limestone, the continuation of that seen in 

 the valley above Recreo. This was found to oveilie a purple lime- 

 stone series which yielded fossils in some abundance. 



The late Dr. Arthur Vaughan, having looked through the speci- 

 mens obtained from this locality, gave it as his opinion that they 

 represent a fauna indicative of the very top of the Lower Carboni- 

 ferous or Avonian secpience, corresponding to the Cyatluixonia 

 Beds (D 2-3) immediately below the Pendleside of the Midlands. 

 They may thus be regarded as being from a somewhat lower horizon 

 than the fauna' previously described by me from the Copacabana 

 peninsula, which was shown to be of Upper Carboniferous or of 

 Pernio- Carboniferous age. 



The more important index-fossils were starred by Dr. Vaughan, 

 and on these his determination was based ; but it must be noted 

 that he had no opportunity of examining the sections of corals, 

 which were not cut until the present year. Although these, for the 

 greater part, belong to new or little-known types, it is interesting 

 to find that they in no way negative his conclusions, which are 

 further supported by stratigraphical considerations, for the lime- 

 stones of the Titicaca district overlie the beds here described. 



Fatjnal List. 



Productus aft", semireticulatus Edmondia sp. 



Martin. „ , ,, 



t> 7 j. js -rwrk -u- Fenestebba sp. 



Productus art. corn D Orbig-ny. „. . .. r „. . , ,™ •„■ \ 



-jtr. 7 x m 7 • • o i F istulinora art. incrustans (Phillips). 



*Productus art. longispinus Sowerby. r 



Rhipidomella aff. michelini *Cyathaxonia aff. rushiana Vaughan. 



(L'Eveille). Cyathaxonid (cf. Gyathaxonia aff. 



*Spirifer bisulcatus Sowerby. costata M'Coy, Vaughan : figured 



Spiriferina aff. cristata Schlotheim. in Q. J. Gr. S. vol. lxii, 1906, 



*Reticularia lineata (Martin). pi. xxix, fig. 5). 



*/imboccelia urii (Fleming). Zaphrentis aff. ennlskilleni 



Seminula aff. ambigua (Sowerby). Milne Edwards & Haime. 



*Retzia radialis Phillips. Lophophylloid Zaphrentis. 



Lophophylloid Caninia (cf. Caninia 



Euomphalus sp. cornucopias Michelin, Carruthers). 



Pleurotomaria sp. Zaphrentis aff. eruca (M'Coy). 



A study of the faunal assemblage enumerated in the above list 

 shows that many of the leading coral groups, characteristic of the 



