ORTMANN : TERTIARY INVERTEBRATES. 77 



states further that he has found at San Jose, in beds immediately over- 

 lying those containing T. patagonica and Monophom, some specimens of 

 Iheringia (Scutella patagonensis), we must distrust his stratigraphical ob- 

 servations entirely ; this observation, if really true, would amount to noth- 

 ing less than to turn the whole stratigraphy of these beds upside down. 

 Such observations must be confirmed and supported by a detailed ac- 

 count of the stratigraphical. conditions, and are worthless if given inci- 

 dentally in 'a few words. It would really be more advantageous for 

 science, if Lahille would stop sneering at and making fun of systematists 

 and descriptive zoology and palaeontology, and would pay more attention 

 to the really vital questions of the stratigraphy of the Patagonian fossils. 



Lahille's material was collected at three different localities : San Jose, 

 Pyramides, and Madryn (Terr. Chubut), but he did not keep these three 

 lots separate. While there is no doubt that he had the true 7\ pata- 

 gonica, some of his figures suggest that also the following species was 

 represented among his material, and especially his figures 56, 57, 58 on 

 plate i resemble the latter. But since he has mixed all three localities, 

 there is no telling whether this is really the case. 



In palaeontological investigation it is not the question to find out 

 whether any allied forms from different horizons may be connected by in- 

 termediate forms, and thus be united into one single variable species, but 

 it is to be investigated whether allied forms from different horizons show 

 a change in the average characters which demonstrates them to be muta- 

 tions in time of one and the same stock. In the present case the latter 

 seems to be true : I have been able to find some constant although very 

 slight differences between the Terebratella from the Patagonian beds and 

 that of the Cape Fairweather beds, a fact that shows clearly that the Cape 

 Fairweather form is to be regarded as a "mutation" of the Patagonian 

 form. If we mingle indiscriminately specimens from both horizons, there 

 is no doubt that we should arrive at the same conclusions as Lahille did, 

 that they belong to one species. This result, however, misrepresents the 

 true condition in nature. 



Record of specimens : Mouth of Santa Cruz River, 28 sp. ; Paso del Rio 

 Santa Cruz, i sp.; Mt. of Observation, upper horizon, i sp.; San Julian, 

 Oven Point, 37 sp. and many fragments; San Julian, Darwin Station, 4 

 sp.; Shore of Salt Lake, i sp.; Upper Rio Chalia, 5 sp.; 30 miles N. of 

 upper Rio Chalia, ca. 25 sp., mostly broken ; Canon near Sierra Oveja, 



