W. M. Gabb on the Cretaceous rocks of California. 229 
cur in the recognized Tertiaries of California. Five of the gen- 
era are peculiar to the Secondary. Anu Ammonite ranges en- 
ely through the group to the top of the highest fossiliferous 
Strata, 
and, the presence of such genera as those in the list given be- 
cat Would point to a very modern era in the Cretaceous, to say 
€ least, 
It must be borne in mind that we have much to learn yet in 
Paleontolog , especially in the matter of the vertical range of 
Sehera. Every year we find genera, nay, whole families, ex- 
‘ending themselves beyond what had been fixed by previous 
‘@uthors as their limits. A few years ago, the presence of imam- 
Malian remains was considered characteristic of the Tertiaries, 
Now we know of Marsupials in the Trias, and who dare say 
that we may not find mammals in Paleozoic rocks? I therefore 
nalntain, that though we have heresuch genera as Aturia, Typhis, 
rdiera, Pseudoliva, Nassa, Mitra, Ficus, Morio, Cerithiopsis, 
Cypreea, and Galerus, still, the only inference that can be drawn 
that the group is on or near the ‘dango of ry ee 
“rbof prophetic member, presaging by some of its genera the 
formations o come, but indissolubly bound by specific ties with 
€ras preceding. 
