244 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



There are several apparently distinct localities and faunas in Brazil 

 which have been called Cretaceous by different authorities. The 

 Cretaceous faunas described by Dr. C. A. White 1 are dissimilar to any 

 other Cretaceous faunas of the continent, and G. D. Harris 2 asserts that 

 they are to all appearances equivalent to the midway stage of the Eocene 

 Tertiary of the Southern Atlantic States. 



Hart and Hyatt have published contributions which undoubtedly 

 show the existence of Cretaceous deposits in Eastern South America 

 very closely allied to those of the Texas region. 3 



The Marine Tertiary — The marine Tertiary and Post-Tertiary sedi- 

 ments of the Gulf Caribbean region, as well as of the Atlantic Coastal 

 Plain of the United States, can all be placed in two broad physical cate- 

 gories, to wit, formations composed of organically derived sea debris,, 

 and formations composed of land wash. 



Formations composed of Sea Debris. — The first class of Tertiary de- 

 posits are chalky or brecciate white or whitish limestones, composed of 

 sea debris, derived from the deposition or trituration of skeletal parts 

 of marine organisms, and of calcareous matter from that which the sea 

 water holds in solution. 



These chalky or clastic limestones sometimes contain a small propor- 

 tion of washed clay, and are always of whitish color. The clay has been 

 thoroughly washed by long presence in the sea. An occasional particle 

 of, pyrites, supposedly an accompaniment of animal decay, may give by 

 oxidation a faint yellowish or cream colored tinge to the rocks, but the 

 darker browns and reds of the first mentioned category are conspicu- 

 ously absent. The white limestone formations have been made in the 

 past of bottom life and accumulations, or as can be seen in process of 

 making to-day, by the wave and current broken and triturated shell and 

 coral material, cemented by the lime derived therefrom. This class of 

 lime formation may become, through interstitial alteration,/irregularly 

 indurated and partially crystalline, and, through solution, cavernous 

 and porous. 



The white limestone formations are found in the Floridian peninsula, 

 but especially abound in the insular areas of Tropical America through- 

 out the Great Antilles, Yucatan, and the Bahamas. It is a singular fact 



1 C. A. White, Contributions to the Paleontology of Brazil, Rio de Janeiro, 1887. 



2 G. D. Harris, Bull, of American Paleontology, No. 4, June 11, 1896. 



8 " Report on the Cretaceous Fossils from Maroim, Province of Sergipe, Brazil, in 

 the Collection of Professor Hartt," Geology and Physical History of Brazil, Hartt, 

 Boston, 1870, p. 392. 



