NIAGABA GROUP. 



311 



Genus LICHAS (Dalman), 1826. 



Paradoxides, Bigsby, Gbeen, 1832. 

 Platynotus, Conrad, 1838. 

 Metopias, Eichwald, 1842. 

 Nuttainia, Portlock (not Eaton), 1843. 

 Platynotus and Arctinurus, Castlenau, 1843. 

 Nuttainia, Emmerich, 1845. 

 Lichas, Loven, Beyrich, 1845. 

 Platynotus, Hall, 1843 & 1846. 



This genus of Dalman had been overlooked by palaeontologists, till revived by Loven and 

 Beyrich in 1845. Dr. Loven's paper fell under my notice as the first volume of Palaeontology 

 was passing through the press, though I did not then give due weight to his arguments, 

 knowing, as I should have done, that his position enabled him to determine by actual com- 

 parison the characters of Dalman's Genus Lichas, which, in his own figures, is not very 

 satisfactory*. The papers of Dr. Beyrich did not come under my notice till a year after the 

 publication of my volume, and therefore I had no opportunity of profiting by the facts there 

 presented. 



The Lockport species, as well as that of the Trenton limestone, will fall under the now well 

 established Genus Lichas. We have also one or more species in the Lower Helderberg lime- 

 stone, and perhaps others may be found. 



672. 1. LICHAS BOLTONI. 



Pl. LXIX ; and Pl. LXX. Fig. I a -I. 

 Paradoxides boltoni, Bigsby, Jour. Acad. Nat. Sci. Phil. 1825, Vol. iv, p. 365. 



— — Green, Monograph, 1832, pag. 6, pi. 1, fig. 5 ; Idem, Monthly Am. Jour. 



Geology, 1832, p. 360. 



— — Harlan, Trans. Geol. Soc. Pa. 1834, Vol. i, p. 103 ; Idem, Med. and 



Phys. Researches, p. 401. 

 Platynotus boltoni, Conrad, Annual Rep. Pal. N. York, 1838, p. 118. 



— — Hall, Geol. Rep. 4th Dist. N. York : Tables of Organic Remains, no. 19. 

 ^rctinurus boltoni, Castlenau, Essai sur le Syst. Sil. de I'Amerique Septentrionale, 1843, p. 



21, t. 5, f. 3. 

 Compare Nuttainia hibernica, Portlock, Geol. Report Londonderry, &c. 1843, pag. 274, pl. 4, 

 fig. 1 J pl. 5, fig. 1 - 3. 



Body and head depressed, axis convex or rounded, lateral lobes often entirely flat ; buckler 

 lunate, extended in front into a kind of proboscis ; glabella convex, broad and prominent in 

 front, separated by a groove from the proboscis, narrowed posteriorly to the middle, and 

 separated by a distinct groove from a large lateral lobe on each side, the base expanded to 



* A note, explanatory of these facts, was printed at the end ol Vol. I, but unfortunately was left out of all except ft 

 few copies of the volume. 



