CHAPTER IX. 

 CRUSTACEANS. 



Lichas boltoni ( Bigsby). 



Paradoxides boltoni Bigsby, 1825: Jour. Acad. Nat. Sci.,Phila., vol. IV, 



p. 362. 

 Paradoxides boltoni Green, 1832: Monog. Trilobites North America, p. 



60, pi. i, tig. 5. 

 Paradoxides boltoni Harlan, 1834: Trans. Gaol. Soc. Pennsylvania, vol, 



I, p. 103. 

 Platynatus boltoni Conrad, 1838: Ann. Rep. False. New York, p. 118. 

 Admurus boltoni Castleman, 1843 : Syst. Sil. de I'Amerique Sept. , p. 21, 



t. V, fig. 3. 

 Lichas boltoni Hall, 1852: False. New York, vol. II, p. 311, pi. Ixx, tigs. 



la-i. 

 Lichas boltoni Meek & Worthen, 1875 : Geol. Sur. Illinois, vol. VI, p. 503, 



pl, XXV, flg. 5. 



Pygidium oval, wider than long, deeply serrate behind. 

 Median lobe narrow, furrows deep; lateral lobes broad, flat. 

 Surface thickly covered with granules. . 



Horizon and localities — Upper Silurian, Niagara? lime- 

 stone : Grafton ( Illinois ) ; also. Pike county % 



Iliaenus graftonensis Mekk & Woethen. 



Illoenus {Bumastus) graftonensis Meek & Worthen, 1869 : Froc. Acad. Nat. 



Sci., Phi)a., p. 54. 

 Illcenus {Bumastus) graftonensis Meek & Worthen, 1875 : Geol. Sur. Illinois, 

 vol. VI, p. 50S, pl. XXV, fig. 4. 



Cephalic shield like in J. insignis, but much broader, 

 elliptic ; eyes small. 



Horizon and localities Upper Silurian, Niagara? lime- 

 stone: Grafton (Illinois). 



