OUTLINES. 
151 
iound in disconnected patches often of quite limited area, and exposed, 
like the preceding, only in river bluffs, ravines, ditches, wells, &c. It 
consists of beds of clay, sand and marl which are locally filled with shells 
(more or less decayed), to a thickness of 2 or 3, to G or S feet, and occa- 
sionally 10 or 20. The distribution of these shell beds, as far as known, 
will be best ascertained by a reference to the maps. These beds of blue 
marl as they are called, are found for the most part in the right banks of 
the large rivers and on the north slopes of the divides or swells of land 
between the rivers, the probable explanation of which has been given in 
the chapter on topography. And the formation thickens, — deepens, to- 
wards the northern border of the State, the beds being much thicker on 
the Tar and Roanoke than on the rivers south ofthein, and in fact being 
of such thickness here as to conceal both the Eocene, if it exists, and 
the Cretaceous, with a few quite local exceptions. 
These shell beds are very rich in fossils, which are often in perfect pre- 
servation. The vertebrates will be found in Cope’s Appendix. The new 
species of shells which have been discovered in the course of the present 
Survey, are described in Conrad’s Appendix. The following list contains 
the species given by Emmons, a few of the names being changed to agree 
with Conrad. 
Echinus Ruffinii, 
Lunulites denticulata, 
“ oblonga, 
Murex umbrifer, 
“ globosa, 
“ sexcostata, 
Ecphora quadrieostata, 
Pyrula spirata, 
“ reticulata, 
Easciolaria distans, 
“ elegans, 
“ Sparrowi, 
*•' alternata, 
“ nodulosa, 
“ acuta, 
Galeodia Hodgii, 
Terebra dislocata, 
“ unilineata, 
“ neglecta, 
Dolium octocostatum, 
Dactylus carolinensis, 
Oliva ancillarioeforinis, 
“ canaliculata, 
Erato lsevis, 
Voluta mutabilis, 
obtusa, 
Amphidetus Virginanus, 
Astrsea bella, 
U 
~ f 
Busycon carica, 
“ contrarium, 
“ canaliculatura, 
“ rugosum, 
Fusus equalis, 
“ exilis, 
“ lamellosus, 
“ moniliformis, 
Cancellaria carolinensis, 
“ reticulata, 
Eupleura caudata, 
Rtycosalpinx multirugatum, 
“ porcinum, 
Buccinum multilineatum, 
“ moniliforme, 
“ bidentatum, 
“ obsoletum, 
Cyprsea carolinensis, 
“ pedicula, 
Mitra carolinensis, 
Marginella olivaeformis, 
“ limatula, 
“ constricta, 
“ ovata, 
