TRENTON LIMESTONE. 
235 
Genus PLATYNOTUS (Conrad).* 
a Depressed, apparently not contractile ; buckler with oculiferous tubercles situated on 
the front or middle lobe ; abdomen with about 12 articulations ; mesial and lateral lobes 
depressed ; ribs with oblique grooves.” 
This description may be amended, so as to read : Buckler five-lobed, or with the central 
lobe trilobate ; oculiform tubercles situated on the outside of the lateral divisions of the 
middle lobe (or of the inner lateral lobes) ; thorax with 11 articulations. 
(These characters will be more fully illustrated under the descriptions of the genera of 
Trilobites.) 
This genus was founded by Mr. Conrad, for the reception of the Paradoxides boltoni of 
the Niagara group. It is clearly distinct from any other established genus, unless it may be 
the Lidias of Dalman. The following species is clearly referable to this genus, possessing 
a very similar character to the P. boltoni. It is also probably identical with JVuttainia 
kibernica of Capt. Portlock, cited helow, being a species of the same genus.f 
296. 1. PLATYNOTUS TRENTONENSIS. 
Pl. LXIV. Figs. 1 a, b, c, d, e. 
JLsaphus? trentonensis. Conrad, Jour. Acad, Nat. Sciences, 1842, Vol. viii, pag. 277, pl. 16, fig. 16. 
Compare JVuttainia kibernica, Portlock, Geol. Rep. Londonderry, 1843, pag. 274, pl. 4, fig. 1 a, b, c, d ; 
and pl. 5, figs. 1,2, 3. 
Buckler ventricose, granulated or pustulate, somewhat five-lobed ; glabella clavate, 
narrow behind, arched and expanded in front, extending beyond the centre of the inner 
* Ann. Geol. Rep. New-York, 1838, p. 118. 
t The very curious reasoning adopted by Capt. Portlock in establishing the Genus JVuttainia of Eaton, lias 
induced me to give the generic description of Platynotus in this place. 
The Genus JVuttainia of Eaton was founded upon a specimen of Trinucleus obtained from the slates of the 
Hudson-river group, near Waterford (New-York), the one which Green afterwards acknowledged to have received 
from Eaton, being the same species on which he founded his Genus Cryptolithus. The JVuttainia sparsa of Eaton 
was a specimen of the central lobe of the buckler of Dipleura ( Homalonotus ) dekayi, preserving a very prominent 
elevated band or articulation at the base, which was mistaken for the front of the buckler. Both the specimens 
alluded to were collected by myself, and are still in my cabinet. 
Although the descriptions of Eaton may have been imperfect, there was no reason for removing the species JV. 
concentrica to the Genus Cryptolithus ; and still less, if possible, for allowing the other fragment to remain as the 
representative of the Genus JVuttainia, when it is unequivocally a part of the Dipleura dekayi. Neither do I con¬ 
ceive it proper to attempt to restore the Genus JVuttainia, by applying the name to so entirely different a form from 
that intended by its author, even should JV*. kibernica be found generically distinct from Platynotus. That genus 
must remain as a synonym of Trinucleus, which has priority of date; though JVuttainia was established before 
Cryptolithus, and, after Trinucleus, is the most appropriate name. The Genus Metopias of Eichwald may, perhaps, 
be identical with Platynotus ; but I have not seen his description of figures. 
The fact that the Genus Platynotus is already in use among the Coleoptera, is not a sufficient argument for 
rejecting it in this place. 
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