8 APPENDIX. 
NAMES. SYNONYMES. 
Cytherea Poulsoni, Conrad. C. globosa, Lea. 
subcrassa, Lea. 
Nuttali, Conrad. 
perovata, etic C. comis, we 
Hydana, $6 Gratelupia Moulinsii, ‘ 
Astarte tellincides, « ; ae i 
Stalagmium margaritaceum,Conrad. Myoparo costatus, 
Corbula oniscus, 4 
nasuta, 66 C. Murchinsonii, « 
Mactra pretenuis, ee M. Alabamiensis, “ 
decisa, . 
parilis, es M. pygmea, * 
Erycina equorea, af Mactra Grayil, _ 
rectilinearis, 4 
Amphidesma linosa, és 
tellinula, is 
profunda, a 
Lutraria papyria, es 
lapidosa, ss 
Psammobia filosa, ke 
eborea, 
Fistulana elongata, Desh. 
Balanus ostrearum, Conrad. 
Serpula ornata, Lea. 
squamulosa, Conrad. 
Dentalium thalloides, + D. alternatum, ts 
—— + 
The Middle Tertiary includes a number of deposits which differ considerably 
from each other in the relative number of extinct and existing species, and their 
age is not clearly ascertained. It may include fossils both of the Miocene and 
older Pliocene periods; to the latter, some deposites certainly belong. I formerly 
applied the term Lower Tertiary to what has been called the Plastic clay of this 
country ; it is now used to designate the oldest of the fossilliferous tertiary beds. 


