TKENTON LIMESTONE. 2.35 



Genus P L A T Y N OT U S (Conrad).* 



"Depressed, apparently not contractile ; buckler witli oculiferous Uibercles sitnaled on 

 the front or middle lobe ; abdomen with about 12 articulations ; mesial and lateral loijcs 

 depressed ; ribs with oblique grooves." 



This description may be amended, so as to read : Buckler five-lolied, or witii the central 

 lobe trilobate ; oculiform tubercles situated on the outside of the lateral divisions of the 

 middle lobe (or of the inner lateral lolies) ; thorax with 11 articulations. 



(These characters will be more fully illustrated under the descriptions of the genera of 

 Trilobites.) 



This genus was foimded by Mr. Conrad, for tin- reception of the Paradoxides boltoni of 

 the Niagara group. It is clearly distinct from any other established genus, unless it may be 

 the Lichas of Dalman. The following species is clearly referable to this genus, possessing 

 a very similar character to the P. boltoni. It is also probal)ly identical with JYultainia 

 hibernica of Capt. Portlock, cited Ijelow, being a species of the same genus. f 



296. 1. PLATYNOTUS TRENTONENSIS. 



Pl. LXIV. Figs. 1 a, b, c, </, e. 



^saphtis? trentoncnxh. Conrad, Jour. Acad, Nat. Sciences, 1SI2, Vol. viii, pas;. 277, pi. Ifi, fig. 10. 

 Compare JS'uttainia hibernica, Pohtlock, Gcol. Rep. Londomlerry, IS 13, pag. 274, pi. -I, fig. 1 a, b, c, d ; 



and pi. 5, figs. 1,2, 3. 



Buckler ventricose, granulated or pustulate, somewhat five-Iobod ; glaltella clavate, 

 narrow behind, arched and expanded in front, extending beyond tiie centre of the inner 



* Ann. Geo!. Rep. New- York, 1S3S, p. US. 



V 



t The very curious reasoning adopted by Cajjt. Portlock in establishing the Genus A''ultainia of Eaton, has 

 induced me to give the generic description oi Platynotus in this place. 



The Genus JVuttainia of Eaton was founded upon a specimen of Trinurlcns 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 J\'ultainia sparsa of E.iton 

 was a specimen of the central lobe of the buckler of Dipltura (Hiimalonoliis) ihhayi, preserving a very prominent 

 elevated band or articulation at the base, which was mistaken for the front of tlie 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 Cryptolitkm ; and still less, if possible, for allowing the other fragment to remain as tlie 

 representative of the Genus JM'uttainia, when it is unequivocally a part of the Dipltura dckayi. 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 sliould .A^. hibernica be found generically distinct from Platynotus. That genus 

 must remain as a synonym of Trinuclttis, which has priority of date ; though JVuttainia was established before 

 Cryptolithus, and, after Trinucleus, is the most appropriate name. The Genus Jtfetopias of Eichwald may, perhaps, 

 be identical with Platynotus ; but 1 have not seen his description of figures. 



The fact that the Genus Platynotus is already in use among tho Coleoptera, is not a sufficient argument for 

 rejecting it in this place. 



3Q* 



