338 
GEOLOGY OF THE FIRST DISTRICT. 
described in the Palaeontological Report. The following have been described by Mr. Conrad, 
in the Annual Reports, viz. 
Cyrtoceras trivalvis. Delthyris acuminata. 
— matheri. Strophomena rugosa. 
Platyceras dumosum, or — undulosa. 
Pileopsis tubifer. 
Odontocephalus selenaius; same as S 
t Calymene odontocephalus.* 
One of the species of Cyrtoceras found in this limestone near Schoharie is figured on PL 
19 of this volume, and was figured by Mr. J. G. Gebhard junior, of Schoharie. Mr. Gebhard, 
in a letter to me, speaking of this rock, says, “ I gave it the name of the Selenurus limestone, 
from the occurrence of that singular trilobite the Odontocephalus selenurus, which occurs in 
that rock, but in no other. The marked and characteristic fossils of this stratum are the 
Odontocephalus selenurus and the Cyrtoceras. I have also discovered in this stratum, frag¬ 
ments of an undescribed trilobite, which, if perfect, would have been at least tioo feet in 
length !! The whole surface is covered with large tubercles and spines. All that I have as 
yet obtained perfect is the post abdomen.” 
Plate 25, fig. 5, shows the position of the strata of the Helderberg division at Schoharie, 
and the upper stratum No. 1 of that section illustrates the position of the Corniferous lime¬ 
stone at that place. 
* The different parts of this trilobite were supposed to belong to different species, and received different names, until an entire 
specimen was found (Vide Prof. Vanuxem’s Report, p. 140). 
