260 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
latitudinal differences are considered, are striking.! In Colombia such 
forms as Gryphea vesicularis, several species of Ammonites figured by 
Karsten, and the Foraminifera, show a resemblance to the Lower and 
Middle Cretaceous of Texas, while.the Ammonites described by Hyatt 
from Sergipe were referred by him to genera and species occurring abun- 
dantly in the Cretaceous of Texas, but unknown to the Californian 
fauna. 
The Antillean Cretaceous cannot here be discussed, for it has not as 
yet been sufficiently studied, but will be defined in our forthcoming 
studies on the island of Jamaica. This is characterized, like the Tertiary 
formations, by certain variations of fauna due to the environment and 
the absence of continental sediments in the waters which these species 
inhabited. 
The Cretaceous faunas of Jamaica, which have been studied in the 
past by others and which I have personally investigated, while specifi- 
cally different from those of the United States, apparently do not con- 
tain a single species which has been found on the Pacific coast. The 
same may be said of the Cretaceous of Santo Domingo, Cuba, and Trin- 
idad, which localities include all we know of the West Indian Cretaceous. 
In the States of Guatemala and Chiapas, Sapper has demonstrated 
and mapped the occurrence of the Cretaceous formations, apparently of 
Atlantic facies, possessing the peculiar genus Barrettia, which has hith- 
erto been found only in Jamaica. 
In the vast stretch of Isthmian country lying between Guatemala and 
the Venezuelan coast, no outerop of the Cretaceous has been reported 
except the one near San José, Costa Rica, described in this report. 
D'Orbigny's conclusions that the oceans were united across the Isthmus 
in Cretaceous times were based upon his identification of five of the 
Cretaceous fossils from the western side of South America with five in 
the Paris Chalk.. The remarkable differences between the synchronous 
Lower and Middle Cretaceous faunas of the California and Texan region 
on the one hand, and the Andean and Venezuelan-Brazilian provinces 
on the other, are so great that in our opinion the only interpretation 
that can be placed upon them, notwithstanding the absence of good 
fossiliferous Cretaceous localities in Central America, is that the waters 
1 Since this paper was written an excellent résumé of the Cretaceous faunas of 
Peru, Venezuela, and Colombia has been printed from the pen of Dr. Gustav 
Steinman, entitled " Beiträge zur Geologie und Paleontologie von Siidamerica,” 
Stuttgart, 1807. It revises the determinations of Karsten, Stellner, and others, and 
presents comparisons and conclusions which the reader should consult. 
