X XXV) 



SYNOPSIS OF GENERA. 



IS77. W :i. Twenty-ninth Rept. N. Y. State Mus. Nat. Hist. 



Is;.. , I telt. Devon. A blag, ties Harzes. 



1379, .. Hall. Trans. Albany Inst., and Twenty-eighth Kept. N. V. State Mas. Nat. Hist. 



[S7<1. Acidaspis, Walcoti Thirty-first Rept. N. V. state Mus. Nut. Hist. 



is: lis, Noi Studieti an Hypostomen i. 



1881 -. Hall. Eleventh Ann. Rept. Geol. Surv. Indiana. 



I^s;;. Acidaspis, Novak. Zur Kennt. bohm. Trilob. 



|ss|. .1 . Novak. Studien an Hypostomen ii. 



Ins.". , Zittbl. Handb. d. Palaeontologie. 



lss;, - .'-in. i'. Revision d. Ostbalt. Silur. Trilob. 



IS87. Acidasp . I brste Bulletin Denison Qniversity. 



Diagnosis. Body depressed-convex. Sur- 

 face ornamented with numerous spines. 

 indistinctly trilobate, with two 

 longitudinal furrows crossing the glabella, 

 produced by the union of the inner ex- 

 tremities of the three pairs of lateral fur- 

 rows. Occipital ring conspicuous. Thorax 

 with from nine to ten segments, each one hearing a strong, nonsulcate ridge 

 on the pleurae, which is produced into a long, hollow spine. Pygidium short, 

 sniall; axis bearing from one to three annulations, and the pleurte usually but 

 a single one. Margins spiniferous. 



Family, Lichad.e. 

 Genus L1GHAS, Dalman. 1826. 



1821. racites, Wahlenberg. Nova Acta Soe, Sci. CJpsala. 

 1822 Trilobites,S hlotheim. Nachtr. iii zur Petrefacktenkunde. 



1822. Pamdoxides, Biiosghiart. Hist. Nat. Crust. Fossiles. 

 1825. Pari ides, Bigsby. Jour. Acad. Nat. Science. 



Asapkus, Dalman. Ueber Palaeaden 

 Ueber Palaaaden. 



1828. Ampyx, Dalman. Ai'sberatt. 



1829. Lichas, lb. 1.7.. Handbuch der Petrefacktenkunde. 



|v;:; P> ''■■ ides,G Monograph of the Trilobites of Noi-th America. 



1835. Lichas, Bronx. Letha:a geognostica. 



• n soeb Lethrea Si ica. 



'••■■•• Rept. Pal. N. V. 

 l-:;;i Arges, Goldi i Nova la i.cad. C. !... \1\. 



1 s " 1 I' - Mn m ln« w:i>- Hi 1 Nat I 'in taces. 



1842. Asaphus, Ci mi. Jour. Acad. Nat. Science. 

 1842. Arges, D'Archiac a rnkuil. Trans. Geol. Society. 



