234 TRANS. OF THE ACAD. OF SCIENCE. 
Comparison.—It will be seen from the description that 
this species resembles the Fenestella retiformis (Me Coy)— 
Keratophytes retiformis (Schlotheim),—but differs in ~ size 
of its interstices, in the large tubercles on the midrib, an 
irregular disposition or the cell pores, and the absence ori in- 
dentatation by those of the fenestrules. 
ote-—There seems to be some discrepancy in McCoy's 
description of F’. retiformis ; it may, however, iat to bea 
typographical error. We are told that the interstices are thin, 
the fenestrules about two thirds the width of the interstices, 
Now this is an impossibility in a mathematical point of view, 
so that some error must have crept into his description. 
Collected by Dr. Geo. G. Shumard, from the Carboniferous 
Limestone of the Organ Mountains, New Me exico. 
_ Escmara(?), CONCENTRICA. ( Prout) 
Conran bon, a swelled at base and bifurea- 
sien j : or 
a ha ta a 
