February 16, 1900.] 



SCIENCE. 



265 



specimens of <S. Ameghinoi, wliioh, according to 

 tlie same author, is found only in the Supra 

 Patagonian (Santa Cruz) beds. Moreover, there 

 are a number of bloclis of the hard matrix 

 from the mouth of the Santa Cruz river and 

 now in our collections in the museum, mingled 

 together in the same block are to be seen various 

 species, some of which, according to von Ihering, 

 are characteristic of the Patagonian and others 

 of the Supra Patagonian (Santa Cruz) beds. 



Dr. Ortman, who is making a thorough study 

 of our collections of Tertiary invertebrates from 

 Patagonia, is entirely unable, from the list of 

 species given by Dr.. von Ihering (page 38), as 

 characteristic of the Patagonian and Supra 

 Patagonian (Santa Cruz) beds, to refer any of 

 the numerous horizons from which our collec- 

 tions have been made to either the one or the 

 other series of beds, on account of the mingling of 

 these alleged characteristic species. He finds 

 represented in our collections from the typical 

 Patagonian beds at the mouth of the Santa 

 Cruz river all but one of the genera and species 

 given by von Ihering (p. 38) as characteristic 

 of the Supra Patagonian (Santa Cruz) beds. 

 This one exception {Valuta ameghinoi) he finds 

 in our collections from the Mt. of Observation 

 associated with Cardium puelchum, Cardiia 

 patagonica = ineequalis, SipJionalia noaohina, 

 which according to von Ihering are character- 

 istic of the Patagonian beds. 



Of the sixty odd species given bj^ von Iher- 

 ing (pp. 6-7) as coming from the Patagonian 

 beds. Dr. Ortman is able to at once designate 

 thirty-five of them as occurring in our collec- 

 tions associated with one or more of the char- 

 acteristic species of the Supra Patagonian 

 (Santa Cruz) beds as enumerated by von Iher- 

 ing (p. 38), while every single one of the latter 

 species has been found with von Ihering' s 

 characteristic Patagonian species. It will thus 

 be seen that it is clearly impossible to distin- 

 guish these two formations by their faunas, 

 while the lithologic characters are even less 

 distinctive. Nevertheless there are in certain 

 instances decided lithologic and faunal differ- 

 ences at the various localities, and it sometimes 

 happens that such differences are quite marked 

 even in the same actual horizon and at neigh- 

 boring localities. To such local differences due 



to the varying conditions attending the deposi- 

 tion of the beds, is due the confusion regarding 

 their stratigraphic relations. Before making 

 more extended observations, the present author 

 like Drs. von Ihering and Ameghino, was in 

 favor of considering these beds as composed of 

 two distinct formations. Subsequent observa- 

 tions, made at many different localities, have 

 convinced me, however, that the Patagonian and 

 Supra Patagonian beds do not represent dis- 

 tinct time intervals, but that sedimentation was 

 continuous from the base to the top of the 

 series, and that the strata of which they are 

 composed all belong to one formation (the 

 Patagonian formation). The rocks composing 

 these beds were laid down, as the fossils clearly 

 indicate, either in a shallow sea or as littoral 

 deposits. The shallow sea deposits constitute 

 the Patagonian phase of the series, while in the 

 Supra Patagonian phase are included the sands 

 and muds that were accumulating simulta- 

 neously along the shores and smaller estuaries as 

 their included fossils clearly indicate. The 

 Patagonian phase prevails at the base and the 

 Supra Patagonian at the top of the series, but 

 neither is restricted to any definite horizon 

 within the limits of the entire series. 



On page 29, Dr. von Ihering enters upon a 

 discussion of the age and relative position of 

 the various sedimentary formations of Pata- 

 gonia, giving a review of the conflicting opinions 

 expressed at different times by various authors 

 on these questions. He also points out the 

 erroneous ideas formerly held by Dr. Ameghino 

 regarding the relative, stratigraphic position of 

 the Patagonian, Supra Patagonian and Santa Cruz 

 beds. In this general resume he has fallen into 

 an error regarding the position taken by my- 

 self in a former paper with reference to the 

 stratigraphic position and age oi the Pyrotherium 

 beds of Ameghino. Since others, more especi- 

 ally Drs. Ameghino and Roth, have also mis- 

 understood the position taken by me at that 

 time on this question I shall improve the 

 present opportunity to explain a little more 

 fully my views concerning the Pyrotherium 

 beds. I did not, as these authors seem to think, 

 place the Pyrotherium beds above the Santa 

 Cruz beds. I placed them in the Cretaceous, 

 where according to Ameghino they belonged. 



