26 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
and on the notes of Steere." Gabb’s opinion of the age of the deposits 
he does not give correctly, but he quotes from Steere’s notes facts that 
appear to strengthen the idea of the Tertiary age of the beds. 
Dr. Oskar Boettger published in 1878 a paper upon the Pebas beds ? 
in which he describes several new species of fossils. He says the fossils 
show the deposits to be of brackish-water origin laid down about the 
mouth of a large stream, that there are no marine forms whatever, and 
while he calls the beds early Tertiary he admits that inasmuch as the 
fauna of the region is unknown, the age of the beds is really doubtful 
(р. 503), — a view with which one must agree. 
Dr. W. Н. Dall writes me privately : * As regards the Pebas fossils, 
they are a unique and isolated group of which it is difficult to deter- 
mine the age because all the characteristic forms are extinct and have no 
obvious relatives. It may be as old as Eocene or as new as Pliocene, but 
not, I think, younger.” 3 
In 1879 Etheridge described a collection made by C. B. Brown from 
similar formations on the Solimões and Javary.* These again are spoken 
of as Tertiary, but no reasons are given for this classification. Most of 
the species described by all these writers are new and the collections 
therefore have but little diagnostic value, especially in the absence of 
a knowledge of the existing fresh and brackish water faunas of that 
region, 
Major Coutinho says that the formations at the mouth of the Huallaga 
in Peru and at the head waters of the Japura, the Juruá, and the Purús 
are the same as those of Marajó and along the coast to Piauhy.5 From 
his description I take this formation to be what Hartt calls Tertiary and 
Agassiz calls glacial sediments. But this sweeping correlation by 
Coutinho must be regarded as extremely venturesome, and certainly with- 
out a sufficient basis of facts. The table-topped hills of the Amazon 
valley Hartt thought were Tertiary, but in these again no fossils were 
found.’ Hartt says in speaking of these formations that his “ opinion 
1 С. Е, Hartt. The Tertiary basin of the Marañon. Amer. Journ. Sci., July 
1872, СТУ., р. 53-58, 
2 Die Tertiärfauna von Pebas am oberen Marañon. Jahrb. а. К. К. Reichsan- 
stalt, 1878, 28 Band, 8 Heft, р. 485-504. 
3 Private letter, April 26, 1901. 
^ В. Etheridge. Notes on the Mollusca... from the Tertiary deposits of 
Solimões and Javary rivers, Brazil. Quar. Journ. Geol. Soc., 1879, ХХХТУ. р. 82-88. 
5 Bull. de la бос, de Geographie. Paris, Oct. 1867, XIV., р. 321-834. 
6 С. Е. Hartt. Recent explorations in the valley of the Amazonas. Ann. Rep. 
Amer. Geog. Soc. N. Y. 1870-71, p. 246. 
