xxxviii SYNOPSIS OF GENERA. 



1^7-J. Lichas, Barrandb. Suppl. Syst. Silur. du Centre 'le la Boheme, vol. i. 



1872 I- has, Katser. Zeitschrifl der deutsch. gwlog. Gesellschaft. 



[S74. Lichas, Steixhardt. In preussisch. Geschieb. gef. Trilobiten. 



I v7 j. Lichas, Billings. Canadian Naturalist and Geologist. 



js7^ Miller Jour. Cincinnati Soc. Nat. Hist. 



1879. / i, . Hall. Twenty-eighth Rept. N. V. State Mus. Nat. Hist. 



1880 / , Novak. Sitzungsber. d Kongl. bohm. Gesellsch. d. Wissenschaften. 



18S2. /,. Silur. i agen 2 und 3, ira Kristianiageb. und auf Eker. 



1884. I i CJndeiBok. ofv. Siljanourad. Trilobit fauna. 



[S85. Schmidt. Mem. de l'Acad. imp. de St. Petersbourg. 



1886. Liclias, Barrois. Ann. de la Societe geol. du Nord. 



]s->7. / Foersti Bulletin Denison University. 



[888. Lichas, Frech. Zeitschr. der deutsch geol. Gesellsch. 



Diagnosis. Body broadly oval. Cephalon transverse. Glabella convex and 

 subdivided by two longitudinal furrows, which are produced by the union of 

 I lie proximal extremities of the lateral furrows. Eyes situated somewhat pos- 

 teriorly. Facial sutures beginning on the posterior margin, near the genal 

 angles, passing forward from the eyes in sub-parallel lines to the anterior mar- 

 gin. Hi/postoma sub-quadrate, with a deep reentrant curve on the posterior 

 margin. Centrum gently convex. Thorax composed of eleven segments. Pleurae 

 sulcate and produced into acute terminations. Pygidium sub-triangular, gently 

 convex. Axis very short, with but two or three annulations. Pleurae broad, 

 sulcate. Margins lobate. 



'»* 



Sub-genus TE RAT ASP IS, Hall. 1863. 



1862. Lichas, Hall. Fifteenth Rept. N. V. State Cab. Nat. Hist. 



1863. Terataspis, Hall. Sixteenth Rept. N. Y. State Cab. Nat. Hist, 

 i 371 .!< idaspis i Terataspis), Hall. Illustrations of Devonian Fossils. 



Diagnosis. Frontal lobe of the glabella 

 ellipsoidal, longitudinally and transversely 

 bisymmetrical, strongly and equally con- 

 stricted on all sides. First and second 

 lateral lobes coalesced and strongly spinose 

 at their summit; third lateral lobe obsolescent or extinct. Glabellar area be- 

 tween the anterior lobe and occipital ring much depressed. Occipital ring broad, 

 bearing strong spines or baculate tubercles. Pygidium with one annulation upon 

 the axis, two or three upon the pleurae, and bearing eight long, recurved, simple 

 or compound marginal spines. 



