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THE NATURAL HISTOR^'S^gjfRJ^.^K/ 2 57 



Order III. PROPARIA Beecher. 



'Tree cheeks not bearing the genal angles. Facial sutures, 

 extending from the lateral margins of the cephalon in front of 

 the genal angles, inward and forward, cutting the anterior 

 margin separately or uniting in front of the glabella. Com- 

 pound paired eyes scarcely developed or sometimes absent in 

 the most primitive family; well developed and schizochroal in 

 the highest family." Beecher, Zittel- Eastman Text Book of 

 Paleontology, p. 633. 



Family 7. ENCRINURIDAE Linnarsson. 



"Cephalon narrow, transverse.' Fixed cheeks very large. 

 Free cheeks long, narrow, separate, sometimes with a free 

 rostral plate between the anterior extremities. Sutures ex- 

 tending from in front of the genal angles obliquely forward, 

 and cutting the anterior margin in front of the glabella. Eyes 

 very small or absent. Thorax of from nine to twelve segments, 

 with ridged pleura. Pygidium generally composed of many 

 segments; limb with strong ribs usually less in number than 

 the annulations of the axis." Beecher, Zittel-Eastman Text 

 Book of Paleontology, p. 634. 



Genus 14. ENCRINURUS Emmrich7i845. 



Cephalon tuberculated, semi-elliptical in outline, the 

 genal angles produced into spines or not; glabella prominent, 

 pyriform, with three pairs of lateral furrows; free cheeks nar- 

 row, separated in front of the glabella by a small rostral plate; 

 posterior limb of the facial sutures cutting the lateral margins 

 just in front of the genal angles; eyes small, more or less elevated 

 on conical prominences or slender stalks. Thorax with eleven 

 segments. Pygidium sub-triangular, the axis long with many 

 more segments than are present upon the pleura. 



Encrinurus egani S. A. M., pi. xxiv, figs. 8-11. 



Description. Cephalon crescentiform with spreading genal 

 spines. Glabella clavate, strongly convex, two and one-half 

 times as broad in front as at the occipital furrow, produced an- 

 teriorly beyond the frontal margin of the head, the lateral mar- 

 gins concave, bounded laterally by deep, abrupt and rather 

 broad dorsal furrows, covered with rather coarse rounded tuber- 

 cles which are more or less regularly arranged in seven or eight 

 transverse rows, the two posterior rows containing three or 

 four tubercles each, while the anterior row may contain as many 



