XXll 
SYNOPSIS OF GENERA. 
1849. Calymene, Salter. Mem. Geol. Surv. United Kingdom, Decade ii. 
1850. 'Calymene, McCoy. Ann. and Mag. Nat. Hist., vol. iv. 
1851. Calymene, McCoy. Synop. Pal. Foss. Wootlwardian Mus. 
1852. Calymene, Barrande. Syst. Sil. d. BohSme, vol. i. 
1852. Calymene, Owen. Geol. Surv. Wis., Iowa and Minn. 
1855. Calymene, Shumard. Kept. Geol. Surv. Missouil. 
1855. Calymene, E.mmons. American Geology. 
1858. Calymene, Bigsby. Quart. Jour. Geol. Soc. 
18(50. Calymene, Hall. Thirteenth Kept. N. Y. State Cab. Nat. Hist. 
1861. Calyme7ie, Hall. Geol. Kept. Wisconsin. 
1862. Caly^nene, McCoy. Synop. Sil. Foss. Ireland. 
1862. Calymene, Hall. Fifteenth Kept. N. Y. State Cab. Nat. Hist. 
1864. Calyme7ie, Salter. Monog. Brit. Tiilobites. 
1865. Calymene, Salter. Mem. Geol. Survey United Kingdom. 
1867. Calyinene, Hall. Twentieth Kept. N. Y. State Cab. Nat. Hist. 
1869. Calymene, Ltnnarsson. Vestergoth. camb. och. silur. Aflag. 
1869. Calymene, Haidenhain. Zeitschi-. d. deutsch. geol. Gesellsch. 
1872. Calymene, Barrande. Syst. Sil. d. Boheme, vol. i, snppl. 
1873. Calymene, Meek. Geol. Surv. Ohio, Palaeontology, vol. i. 
1875. Calyonene, Meek. Geol. Surv. Ohio, Palaeontology, vol. ii. 
1876. Calymene, Hall. Illustrations oFDevonian Fossils. 
1876. Calymene, Rcembr. Lethaea palaeozoica. 
1878. Calymene, Angelin. Pal. Scandinavica, pt. i. 
1879. Calymeiie, Ulrich. Jour. Cin. Soc. Nat. Hist., vol. ii. 
1879. Calymene, Novak. Studien an Hypostomen, i. 
1880. Calymene, Vogde.s. Proc. Acad. Nat. Sci. Phil. 
1881. Calymene, Hall. Eleventh Kept. Geol. Surv. Indiana. 
1881. Calymene, Walcott. Bull. Mus. Comp. Zoology, Harvard Coll. 
1883. Calymene, Novak. Zur Kenntn. bohmisch. Trilob. 
1884. Calymeiie, Novak. Studien an Hypostomen, ii. 
1885. Calymene, Zittel. Handb. d. Palaeontologie. 
1885. Calymene, QUhlert. Bull, de la Soc. d’Etudes scientif. d’Angers. 
1887. Calymene, Foerste. Bulletin, Denison University. 
Diagnosis. Body oval. Cephalon semicircular, 
nearly three times as wide as long; rounded in 
front, genal angles blunt, rarely produced into 
spines. Anterior margin somewhat elevated ; gla¬ 
bella strongly arched, sharply limited by deep dor¬ 
sal furrows, and divided into three pairs of sub-spherical lobes, by the unequal, 
short lateral furrows, the posterior pair of which bifurcate near their proximal 
extremities. Cheeks convex, and with a distinct marginal border. Eyes situated 
somewhat anteriorly ; visual surface small, homocorneal. The facial sutures 
begin at the genal angles, and pass in a sigmoid curve to the eyes, thence, 
parallel to the axis, to the anterior margin, where they are united by the 
