ORTMANN I TERTIARY INVERTEBRATES. 



279 



Of these 29 species, 19 have been found at Santa Cruz. This horizon, 

 the lowermost in this section, ought to be Juliense, and, indeed, it con- 

 tains 5 Juliense species ; but this conclusion is entirely upset by the fact 

 that 3 Leonense and 4 Suprapatagonian species are* also represented here. 



400 above base. 



Only Modiola andina has been collected here. 



600 above base (or 100' below top of marine series). 



* Terebratella dorsata. 



J * Terebratella patagonica. 

 *Nucula patagonica. 

 *Leda errazurizi. 



* Glycimeris ibari, 



L *Perna quadrisulcata. 

 L & S * Ostrca ingens. 

 J& S *Pecten geminatus. 

 Modiola andina, 



* Crassatellites quartus. 

 Cardita volckmanni. 



* Cardium philippii. 



* Venus meridionalis. 



* Venus volckmanni. 

 Mactra garrctti. 



*Parwpea regularis. 

 *Panopea quemadcnsis. 

 *Martesia patagonica. 

 *Solariclla dautzenbergi. 

 *Gibbula lavis. 

 *Gibbula dalli. 



* Infundibulum corrugatum. 



Galerus araucanus. 

 L *Turritella ambulacrum. 



Vermetus cf. intortus. 

 S * Struthiolaria ameghinoi. 

 *Pyrula Carolina. 

 J Siphonalis noachina. 



* Trap/ton patagonicus. 

 S Valuta ameghinoi. 



* Terebra costellata. 



* Geryon peruvianus. 



The comparison of this locality with others is very important and inter- 

 esting. About half (15) of the number of species are identical with those 

 of the lowermost horizon of this section, although both are separated from 

 each other by almost 600 feet of deposit. In this locality, out of 32 

 species, 25 are common to the type-locality at Santa Cruz, and this shows 

 conclusively that the three (Santa Cruz, lower and upper horizon of Rio 

 Tarde section) cannot be separated, and further, it shows that at Santa 

 Cruz no two or more horizons can be represented, since the latter section 

 comprises only about 250 feet, while here, at 600 feet above the base, still 

 an unmistakable Patagonian fauna (as found at Santa Cruz) is present. 

 Comparing our list with the subdivisions of Ameghino and v. Ihering, 

 we see that we have here again, at 600' above the base, and 100' below 

 the top, where we should expect a characteristic Suprapatagonian fauna, a 

 mixture of 3 Juliense, 3 Leonense, and 4 Suprapatagonian elements, a 

 relation that has hardly changed from that found at the base of the Rio 

 Tarde section. 



Extreme top of marine series (Rio Tarde section). 



Ostrea ingens has been found here in a form (see p. 109) that corre- 

 sponds to O. hatcheri, which is found, according to v. Ihering and 

 Ameghino, exclusively in the Leonense beds. 



