162 Mesosoic Se7'ies of JVew Mexico. — Marcou. 
Corresponding 
to Nebraska 
eectiouB 2 and 3 
Feet. 
I. G. white limestone ..2") ' 
. F. Yellow limestone. 50 1 
.E. Blue clay 
.D.White sandstone.. 
C. Yellow sandstone.: 
' B. White .sand stone. 
Keupe'r."* 
j^ A. Grayish blue clay. 1 
<^ a. Zone oi the Gryphsea 
^ dilatata var. tucumcarii 
o and Ostrea marshii iu 
■J*, division E. Blue clay. 
"The explanations of the section quoted above are those 
given by Mr. Marcou. The designations at the right hand are 
those given by him in the text accompanying the section." — 
The designations given at the left hand are those given by 
Mr. Hall (Mexicmi ioundar^y line, p. 135, vol. i, Washington, 
1857). 
Mr. Hall adds, p. 136 : "Having examined the specimens 
in Mr. Marcou's collection from this locality I have no hesita- 
tion in saying that the specimens labelled by him as Grt/plicca 
tacumcarii (G. dilatata yslv. tucumcarii, J3till. soc. geol. de 
France, tome xii, pi. 21) are the Gryphcea pitcheri of Morton 
and present no features either in forms,characterS;Or condition 
of preservation, or otherwise, which can serve to distinguish 
them from Gryphcea pitcheri, in the boundary survey collec- 
tions, from strata forming a continuation of the Llano 
Estacado." 
Mr. Hall has figured and described my specimens from 
Pyramid mount, and from Comet creek, in Paciiic. li. E. 
explorations, vol, iii, pp. 99-100. The G. tucumcarii figured 
was chosen from some rolled and badly preserved specimens; 
