278 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



Of these 19 species, 16 (marked *) are found at Santa Cruz, which 

 would make these beds identical with those of the type-locality. The 

 fact, that Juliense, Leonense, and Suprapatagonian species although 

 only a few of each category are associated here, is in so far interesting, 

 as it shows that these three supposed different divisions are condensed 

 here into only 100 feet. 



LAKE PUEYRREDON. 



East end of Lake Piieyrredon; horizon not ascertained. 



J * Rhynchonella plicigera. L & S * Ostrea ingens, * Cardium philippii. 



* Terebratella dorsata. J& S *Pecten geminatus. 



All of these 5 species have been recorded from Santa Cruz, and, 

 although the number of species is very small, we have a mixture of 

 Patagonian and Suprapatagonian forms. According to the matrix and 

 the species found, this horizon seems to correspond to the lowermost of 

 the Rio Tarde section (see below). 



High bhtffs, S. IV. of Lake Pueyrredon; horizon not ascertained, but 

 about 1000' below Santacruzian beds. 



J * Rhynchonella plicigera. Magellania lenticitlaris. Grypluza cf. tarda. 



Rhynchonella squamosa. J * Terebratella patagonica. 



This horizon also seems to correspond to the lowermost of the Rio 

 Tarde section. 



LAKE PUEYRREDON, Rio TARDE SECTION, 700' thick (see Hatcher, 

 1 900 a, p. 100). 



Base of marine Tertiary : The lowermost beds of the Rio Tarde sec- 

 tion, immediately overlying a basaltic deposit that lies on top of the 

 barren Cretaceous sandstones. 



*Cidaris antarctica. L *Perna quadrisulcata. *Dentalium sulcosum. 



J Scutella patagonensis. L & S * Ostrea ingens. * Gibbula lizvis. 



Cyrtoma posthumum. J& S *Pecten geminatus. S *Scalaria rugulosa. 



J * Rhynchonella plicigera. Modiola andina. L * Turritdla ambulacrum. 



Rhynchonella squamosa. Crass ate llites longior. S * Strut] dol aria ameghinoi. 



Magellania lenticularis. * Cardium philippii. * Trophon patagonicus. 



* Terebratella dorsata. * Cardium pisum. Urosalpinx pyriformis. 

 J * Terebratella patagonica. * Venus volckmanid. Balanus cf. psittacus. 



J Bouchardia zitteli. *Panopea regularis. Balanus varians. 



* Glycimeris ibari. *Panopea quemadensis. 



