724 



AETHROPODA 



PHYLUM VII 



epistomal plate ; eyes small, elevated on conical prominences ; thoracic segments 



eleven : pygidium elongate, triangular. Ordo- 

 vician and Silurian ; Europe, Asia, and America. 

 Gybcle Loven. Similar to Encrinurus, but 

 with the ribs of the pygidium turning back 

 sliarply, parallel to the axis. Ordovician and 

 Silurian ; Euroiie and America. 



Encrinurus punc 

 tatus Emmrieh. Sil 

 urian ; Gotland. 



Calymenidae Milne Edwards. 



Fig. 1400. 



Fig 13'^t9 



Encrinnrus hohemicns 



(Barrande). Silurian tti -i o 



(Etage E) : Loehkow, l^amily 2. 



Bohemia. ... 



Propana with thirteen segments, the hypo- 

 stonm notched hehind, and attached to an epistomal plate. Free cheeks narrow, the 

 facial sutures cutting the 

 margin almost exactly:\in 

 the genal angles. Ordovician 

 to Devonian. 



Calymene Brongniart 

 (Figs. 1398, G; 1401). 

 Glabella prominent, strongly 

 lobed, with two or three 

 pairs of lateral furrows. 

 Ordovician to Devonian ; 

 Europe, Asia and America. 



Pharostoma Corda. 

 Glabella prominent, very narrow at the front, with 

 two pairs of glabellar furrows. Long genal spines 

 present. Ordovician ; Europe. 



Homalonotus Koenig. Axial lobe wide, cephalon 

 short and trilobate in front, cheeks forming high 

 mounds crowned by the eyes. Silurian ; Europe 

 and Nova Scotia. 



Trimerus Green (Fig. 1402). Cephalon longer 

 than in the preceding, not trilobate in front, free 

 cheeks narrow. Silurian and Devonian ; woild-wide 

 distribution. 



Dipleura Green (Fig. 1398, D). Axial lobe wide. 

 Pygidium smooth. Devonian ; Europe and America. 



Fig. 1401. 



Calymene meeki Foerste. 

 Ordovician ; Cincinnati, Ohio. 



Family 3. Oheiruridae Salter. 



Fig. 1402. 



Trimerus clelphiitocephalus Grfien. 

 Silurian ; Lockport, New York. 



Proparia with small free cheeks, whose anterior ends 

 are separated by the glabella. Pygiditim small with 

 pleura ending in spines. Thorax with nine to eighteen segments. Ordovician to Devonian. 



Subfamily A. Cheirurinae Raymond. 



Oheiruridae with eleven segments in the thorax {rarely nine to thirteen), and four 

 segments in the pygidium. 



Cheirurus Beyrich (Figs. 1398, E ; 1403). Glabella smooth, more than one-third 

 the total width of the ceplialon ; pygidium with six or seven sub-equal spines. 

 Ordovician and Silurian ; Europe, Australia and America. 



Geraurus Green (Fig. 1341). Glabella pustulose, one-third or less the total width 

 of the cephalon ; pygidium very small, with the first pair of sj^ines very long, the 

 others short or absent. Ordovician ; Eurojje, Asia, and America. 



