76 
are complete from side so side, are four in number. 
The imperfect additional ones, vary from two to 
four; the smallest and inner, consisting only of two— 
or three punctures. A plain edging includes the se- 
micircle of punctures. In the beds of these casts, | 
the places of the punctures are shown by small coni- 
cal elevations, and those of the ridges of the net-work, 
by corresponding depressions.” 
Should this prove to be a distinct species, we pro-. 
pose to call it Cryptolithus Bigsbii. 
The Nuttainia Concentrica of Professor Eaton seems 
also very nearly ailied to this species; he describes 
it as having “four or five concentric arcs of punc- 
tures in front of the buckler, sepa by alternating . 
arcs of fine elevated ridges.” The genus Nuttainia, 
to which We refers this species, cannot include it, 
and the N. Sparsa; for these two relics have scarce- 
ly a single essential character in common; we have, 
therefore, confined the genus Nuttainia, to the spe- 
cies which he calls Sparsa. | 
The Cryptolithus Tessellatus is very common at 
Trenton falls. In the transition limestone at Glenn’s 
falls, in the state of New York, during a very short 
visit to this place, Dr. R. Harlan procured a large © 
number of this fossil, but only the buckler, the 
projecting front of which exhibited a pisiform pro- 
tuberance above the level of the strata. Mr. 
Eaton says that the N. Concentrica “occurs in the 
-wacke variety of transition of argillite,on the C ham- 
plain canal,” between the town of Waterford and the 
one —— 
See ee > ae 
