xl 
SYNOPSIS OF GENERA. 
Sub-genus ARGES, Goldfuss. 1839. 
1837. Calymene, Green. Am. Jour. Science. 
1839. Arges, Goldfuss. Nov. Act. Acad. Caes. Leop. Car., vol. xix. 
1843. Arges, Goldfuss. Neues Jarhb. fiir Min. 
1840. Lichas, Barrandb. Notice prelim, sur le Syst. sil. BobSme. 
1840. Arges, Beyricii. Untersuchungen iib. Trilob. 
1847. Cory(locey)lialus, Acanthopyge, partbn, Corda. Prodrom Monog. bohm. Trilob. 
1852. Arges, Hall. Pal. N. Y., vol. ii. 
1852. Lichas, Barrande. Syst. Sil. Bobfime, vol. i. 
1857. Lichas, Nieszkowski. Monog. Trilob. Ostseeprov. 
1858. Lichas, Hoffmann. Ti-ilobit. Russlands. 
1878. Z'icAas, Angelin. Palieontologia Scandinavica. 
1885. Arges, Schmidt. Revision Ostbalt. Silur. Ti-ilob. 
Diagnosis. Middle lobe of the glabella 
sub-rectangular, longitudinally arched, often 
spiniferous. Second lateral lobes larger than 
the first; third lateral lobes inconspicuous or 
obsolete. Palpebral furrows indistinct. 
SuB-GENUS CERATOLICHAS, n. sub-gen. 
Diagnosis. Frontal lobe ellipsoidal and 
strongly convex, faintly constricted on the 
abrupt and almost vertical posterior slope. 
The elevated posterior edge of this lobe bears 
two or four long recurved spines. The lateral 
lobes are very depressed and obsolescent, the 
first and second pairs coalesced, and the third 
pair either obsolete or represented by faint 
tubercles in the occipital furrow. Just within 
each palpebral lobe is a slender spine, and 
the occipital ring bears a long central recurved double spine. 
Ceratolichas differs from Conolichas, Dames, in the depressed and obsolete lateral 
lobes; from Terafaspis, Hall, in the sub-quadrate, slightly constricted frontal 
lobe, and from Arges, Goldfuss, in having the frontal lobe shorter, more ele¬ 
vated, and abruptly sloping toward the posterior extremity. 
