284 
PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
Of the Santa Cruz blocks, all except 1 and 3 are still intact. 1 has 
been broken up completely, while of 3 a part remains intact. 
This line of evidence demonstrates clearly that of the 36 characteristic 
species introduced by Ameghino and v. Ihering, at least 20 are to be 
dropped; of 13 of them it has been shown (see list, p. 283) that they are 
found anywhere within the marine series underlying the Santacruzian 
beds, and 7 more (aside from 5 that are included in these 13) have been 
found associated with each other in such a way in the matrix that they 
are to be looked for at any horizon within this series. 
Of the remaining 16 species, 13 belong to the rarer forms, and, on that 
account, are unfit to be used as characteristic fossils ; the remaining 3 
are Cucullcea a/fa, Dosinia Iceviuscula and Siphonalia dilatata. These are 
said to be Patagonian (Leonense) species, and have been found exclu- 
sively in the neighborhood of the mouth of the Santa Cruz River. This 
fact — considering the close relations of the fauna of Santa Cruz to those 
of other localities — does not permit them to be used as characteristic fos- 
sils for any definite horizon, but rather demonstrates that they should be 
regarded as local elements of this particular locality (see p-. 285). 
Taking together all the foregoing considerations, we arrive at the follow- 
ing conclusions. 
It is impossible to assign — according to the palaeontological evidence- — any 
of our Patagonian localities to any of the subdivisions distinguished by 
Ameghino. Not only are we unable to separate the Juliense and Leonense 
subdivisions of the “ Patagonian formation f but also we are at a loss to 
draw a line between the “ Patagonian formation ," and the lower , marine 
part of the “ Santacruzian formation, which has been called by Ameghino 
“ Piso Suprapatagonico. litis conclusion is fully supported by the strati- 
graphical observations made by Mr. Hatcher, who will elsewhere discuss 
this question from the point of view of stratigraphy. 
The palceontological characters of the different subdivisions given by 
Ameghino and (_ following him) by v. Ihering are, accordingly , of no use, 
and have no significance at all. Patagonian and Suprapatagonian beds 
form a palceontological unit, with one and the same fauna going through 
from top to bottom, without any remarkable change} The terms “ Supra- 
1 But slight traces of a change in the fossils have been noticed ; see under Ostrea ingens and 
Terrebratella patagonica. 
