632 



AKTHROPODA 



SUB-KINGDOM VII 



lateral margins separately. 



(Et. 



FIG. 1310. 



Konieprus, Bohemia (after Barrande). 



Eyes crescentic. Thorax of ten segments, with ridged pb'.urn. 

 Pygidium longer than cephalon or thorax ; axis 

 very short, with radiating furrows extending 

 from it across the broad limb toward the margin; 

 doublure very wide; margin generally entire. 

 Ordovician to Devonian. 



Tliis comprises the single genus Eronteus, 

 Goldfuss (Figs. 1264, 1288, H, 1310). Ordo- 

 vician to Devonian ; Europe and North 

 America. Most abundant in the Silurian and 

 Devonian of Bohemia. 



Famil 6. Lichadidae. Barrande. 



Dorsal shield generally large and flat, with granulated test. Cephalon small, not 

 more than one-fourth the entire length ; genal angles spiniform. Free cheeks separate'; 

 sutures extending from the posterior margin obliquely inward to the eyes, and then almost 

 directly forward, cutting the margin separately. Glabella broad, ivith a large, often 

 tumid central lobe, and from one to three side lobes. Eyes not large. Thorax with nine 

 or ten segments, and grooved and falcate pleura. Pygidium large, flat, commonly with 

 toothed, or notched margin corresponding to the pleural grooves ; doublure very broad. 

 Ordovician to Devonian. 



Most of the forms of this family are above the average size of Trilobites, and 

 several species are among the largest of the class. 

 They are all thin-shelled, and so loosely articu- 

 lated that entire specimens are extremely rare. 



Lichas, Dalmaii s. str. (Figs. 1262, 1311). 

 Anterior lobe of the glabella dominating the 

 other lobes, and continuous with the axis ; 

 lateral lobes reniform and small. Ordovician 

 and Silurian ; Europe and North America. 



Sub-genera : Arges, Goldf. (Fig. 1 3 12). Lateral 

 lobes of glabella strongly defined, nearly as large 

 as the central one, and divided transversely by a 

 furrow ; lobes and neck ring often spiniferous ; 

 pygidium with dentate margin and spiniform Sweden (after 



1 * fe \ Angelm). 



pleural extensions. Silurian and Devonian. 



Dicranogmus, Corda (Fig. 1313). Glabella divided by two longitudinal and one 

 transverse furrow into angular lobes ; pygidium with simulated axis ; limb with a 



few short denticula- 

 tions. Silurian. 



Conolichas, Dames 

 (Fig. 1314). Glabella 

 having one large pro- 

 truding central, and 

 two prominent lateral 

 lobes, with sometimes 

 two smaller basal 

 lobes. Ordovician to 

 Devonian. 



Ceratolichas, Hall 

 and Clarke (Fig. 



1315). Central lobe arched, tumid, with smaller side lobes ; central lobe and occipital 

 ring with long curved spines. Devonian ; North America, 



Arges armatiiA, Gold- 

 fuss. Devonian ; Ger- 

 many (after Beyrich). 



FIG. 1313. 

 Dicranogmus 

 jiti/nniiriis, Hall 

 and Clarke. Sil- 

 u r i a n ; New 

 York. 



FIG. 1314. 



i 'onolLhas Schmidti, Darnes. 

 Ordovician ; Germany (after 

 Dames). 



Fio. 1315. 



Ceratolichas gryps, Hall 

 and Clarke. Devonian ; New 

 York (after Hall and Clarke). 



