XXXIV 
SYNOPSIS OF GENERA. 
Sub-genus CORYCEPHALUS, n. sub-gen. 
Diagnosis. The entire frontal and lateral 
margins of the cephalon bear a single row of 
widely separated denticulations, which may 
be acute and triangular or broad and sub¬ 
quadrate. 
Sub-genus CHASM OPS, McCoy. 1860. 
1837. Asaplms (partlm), Murchison, Silurian System. 
1838. TriluMtcs (partim), Saks and Boeck. Giea Norvegiea. 
1843. Phacups {parthn), Portlock. Geolog-. Kept. Tyrone. 
1845. Pkacops (partim), Emmiuch. Neues Jahrb. fiir Min. 
1846. PJiacops (partim), Burmeister. Oi-ganiz. Ti-ilobites. 
1848. Dahnanla, Salter. Mem. Geol. Surv. United Kingdom. 
1849. P/iaco 2 )S (partwi), Salter. Mem. Geol. Surv. United Kingdom. 
1850. Chasmops, McCoy. Ann. and Mag. Nat. Hist. 
1851. Cliasmo 2 }s, Odontocliile, McCoy. Synops. Pal. Foss. Woodwardian Mus. 
1852. CJiasmo 2 )S, Angelin. Palasontologiea Suecica. 
1853. PJiacops (Dalmania), Salter. Geol. Surv. Decade vii. 
1864. CJiasmops, Salter. Monogr. Brit. Trilobites. 
1869. Pliaccqis (partim), Linnarsson. Verstergotl. camb. och. silur. Aflag. 
1874. PJiacops (piartim), In pi-euss. Geschieb. gef. Trilobit. 
1876. Dahnanites (partim). Hall. Illustrations of Devonian Fossils. 
1876. CJmsmo 2 }S, C. F. RoiMER. Lethsea palieozoica. 
1878. PJtaco 2 >s (partim), Angelin. Palaeontologia Scandinavica. 
1885. CJiasmops, ZiTTHh. Handb. der Palieontologie. 
Diagnosis. Genal angles usually produced into 
spines. Frontal lobe of the glabella large, trans¬ 
verse and not intersected by the facial sutures. 
Lateral lobes unequal, the first and second pairs 
being coalesced and the third pair nearly obso¬ 
lete. Pygidium large, sometimes with a terminal 
spine. 
