A MA ZONIA N UPPER CA RB ONI PER O US PA UNA . 483 



are evidently the prolongation of the table-topped hills of 

 Parauaquara and Almeirim to the eastward of the limits of the 

 map. Presumably the Tertiary beds cover, or have covered, a 

 large part of the areas left blank on the map. 



A full list of the fauna, so far as known, is given in the fol- 

 lowing table with the distribution of the species in the different 

 localities. Out of the total number of 122 species 62 have been 

 found in the limestone of Bom Jardim near Itaituba, which, 

 being the formation from which the most complete collections 

 have been made, and apparently also the richest in species, 

 may be taken as the standard with which the others may be 

 compared. The silicified specimens found free on the beach at 

 Itaituba are evidently washed out of a decayed limestone, and 

 the character of the specimens as well as the numerical compari- 

 son indicates its complete identity with that of Bom Jardim, 

 since of the 33 species recognized on the beach, only five rare 

 forms of Bryozoa, Echinoderms, and Eusulina have not as yet 

 been found in the limestone. 



The peculiar siliceous boulders have every appearance of 

 being weathered out of a limestone bed and their position on the 

 beach at Itaituba indicates that this bed was intimately associated 

 with that furnishing the loose beach specimens, if not identical 

 with it. Of the 32 species recognized in the boulders, 13 have 

 not been found in the limestone, and of these 10 (six being gas- 

 teropods) have not been found in the other Itaituba rocks 

 though two of these occur in the shale of Pacoval on the Curua 

 The fauna of the boulders is characterized by the abundance of 

 lamellibranchs and gasteropods, making up two-thirds of the 

 species, and the differences between its fauna and that of the 

 limestone are presumably of habitat rather than of horizon. 

 Large coarse forms predominate and are for the most part so 

 rare that no certain conclusion regarding them can be drawn. 

 The exceptions are Streptorhynchus correia?ius and Productus corn, 

 which are abundant and characteristic. The former has not 

 been found in the other rocks at Itaituba, though it occurs else- 

 where, and the absence from the limestone of the latter, one of 



