ARCHIVOS DO MUSEU NACIONAL 
é tanto mais interessante quanto as res- 
pectivas faunas paleozoicas dos dous con- 
tinentes (especialmente a Carbonifera) são 
quasi identicas. (”) Deve-se comtudo notar 
que diversos typos genericos d'estes Gas- 
teropodes Cretaceos brazileiros não eram 
conhecidos até hoje, e que, com poucas 
excepções, todas as especies são novas. A 
preponderancia d'estes typos dá a toda a 
fauna um aspecto particular, mas algumas 
das differenças mencionadas são mais 
fundamentaes do que denota a simples 
variação especifica. 
Hoje é bem sabido pelos paleontolo- 
gistas, que certos typos isticos da 
fauna de um certo período geologico de 
qualquer parte do mundo podem ser en- 
conirados em outras partes como consti- 
tuintes de faunas de outros periodos, mas 
não remotos. Este facto é confirmado 
pela presença já mencionada de especies 
de aspecto jurassico nesta fauna cretacea 
“brasileira, e ainda pela presença de certos 
typos, especialmente entre os Gastero- 
podes, que, encontrados sós, podiam ser 
com razão referidos ao periodo terciario. 
Refiro-me especialmente às especies de 
Fusus, Murex, Phorus, etc., que são 
descriptas nas paginas seguintes e figu- 
radas nas estampas annexas. Apezar da 
presença nesta fauna cretacea brazileira 
de alguns typos que são respectivamente 
(*) Vide Rathbun — The Devonian Brachiopoda of Ereré, ete, Rc 
Annals of the Lyc 
of the € 
f the Mus. of Comp. Zoo 
4874; Proc. of the Boston Soc. Nat. Hist. 1878; 
Carboniferous Brachiopoda of ranice Bull. 
Fossils from Lake Titicaca. Bull. 
17 
interesting because the Palaozoic (espe- 
cially the Carboniferous) faunas of the 
two continents respectively are so nearly 
identical. (*) It should be remembered 
however, that several of the generic 
types among these Brazilian Cretaceous 
Gasteropods have not hitherto been 
known, and that with few exceptions, all 
the species are new. The conspicuousness 
of these types gives a unique aspect to the 
whole fauna, but still some of the differ- 
ences which have been referred to are 
more fundamental in their character than 
is implied in mere specific variation. 
tis now well understood by palagon- 
tologists that certain of the types which 
characterize the fauna of a certain geolog- 
ical period in any one part of the world, 
may be found as component parts of fau- 
nas of other, but not remote, periods in 
other parts. This fact is illustrated by 
the already mentioned presence of species 
in this Brazilian Cretaceous fauna which 
have a Jurassic aspect. It is still further 
illustrated by the presence of certain 
types, especially among the Gasteropods, 
which might, if found alone, be reasona- 
bly referred to the Tertiary period. 1 refer 
especially to the species of Fusus, Mu- 
rex, Phorus, ete., which are described in 
the following pages and illustrated on the 
accompanying plates. Notwithstanding 
the presence in this Brazilian Cretacegus 
of the Buffalo Soc. Nat. His 
m of Nat, Hist, n. 9. 1875. donas 
« AST4; Notice of the Palzozoic 
Ve vas 
ornell tuideraro “Vol 
« 1876. 
