268 
PATAGONIAN EXPEDITIONS ! PALAEONTOLOGY. 
impossible. That this is not due to defective observation, will be shown 
further on, and it will be demonstrated, that the palaeontological charac- 
ters given by Ameghino do not hold good in the face of a careful com- 
parison with our material. 
Ameghino (1899) gives the following characteristic fossils for his sub- 
divisions. 
Piso yuliense : 
Hyp echinus patagonensis. 
Echinarachnius juliensis ( = Scutella pata- 
gonensis). 
Schizastcr ameghinoi. 
Terebratula patagonica (= Terebratella p.). 
Rhynchonella plicigera. 
Bouchardia zitteli. 
Pecten gcminatus . 
Pecten prcenuncius. 
Siphonalia noachina. 
Piso Leonense : 
Ostrea percrassa (= 0. ingens). Turritella argentina (= T. ambulacrum). 
Perna quadnsulcata. Struthiolaria ornata. 
Cucullcza alta. 
Piso Suprapatagonico : 
Ostrea patagonica (= 0. ingens). 
Pecten quemadensis (= P. geminatus). 
Cytherea splendida (= Meretrix iheringi). 
Amathusia angidata. 
Dentalium octocostatum {= D. octocostellatum). 
Valuta ameghinoi. 
It is most important to know, where we are to look for the type-locali- 
ties of these divisions. In this respect Ameghino is remarkably careless ; 
indeed, he does not say in any case, what we are to take for typical rep- 
resentations of his divisions, and thus we have to guess, or rather to infer 
from the names given, which one is the locality intended in each case. 
The Piso yuliense is apparently called after San yulian , and this we must 
take for the type-locality of it (see below). The Piso Leonense has been 
named apparently from Ml. Leon at the mouth of the Santa Cruz River, 
and thus those beds, of which the list of fossils is given above, are to be 
taken as representation of this division. And indeed, all five species, 
mentioned by Ameghino as characteristic of this subdivision, have been 
found at the mouth of the Santa Cruz River, and further, since two of 
them, Cucullcea alta and Struthiolaria ornata , have been found nowhere 
