THE NATURAL HISTORY SURVEY. 26 1 



their anterior extremities in front of the glabella; eyes small; 

 hypostome sub-quadrate, notched. Thorax with thirteen seg- 

 ments, the axis strongly convex and bounded by deep axial 

 furrows; pleural lobes wider than the axis, bent down laterally. 

 Pygidium distinctly marked off from the thorax, with six to 

 eleven segments, the axis prominent and the margin entire. 

 Calymene niagarensis Hall, pi. xxm, figs. 9-10. 



Description. Body strongly trilobate, sub-ovate in outline, 

 greatest breadth at the posterior margin of the cephalon, becom- 

 ing gradually narrower to the junction of the thorax with the 

 pygidium, then narrowing much more rapidly to the posterior 

 extremity of the pygidium. When enrolled the body is sub- 

 globular. 



Cephalon short and broad, from two to two and one-half 

 times as wide as long, anterior margin most sharply rounded in 

 front, then sloping away to the genal angles with a gently convex 

 curve. Glabella strongly convex, elevated above the cheeks, 

 sharply defined by the deep dorsal furrows, broadest across the 

 posterior lobes where it is as wide as long, broadly rounded or 

 almost truncated in front ; frontal lobe occupying less than one- 

 third the length, transversely sub-semielliptical in outline; 

 first lateral lobes very small, scarcely separatedTTrom the frontal 

 lobe; second lateral lobes larger and node-like; posterior lobes 

 much larger, forming a pair of conspicuous sub-globular nodes 

 at the base of the glabella. Lateral furrows not extending 

 across the median portion of the glabella; anterior pair scarcely 

 recognizable, occupying only the lateral slopes of the glabella; 

 second pair more conspicuous, rounded in the bottom, nearly 

 confined to the lateral slopes of the glabella; posterior pain 

 much broader and deeper, broadened or slightly bifurcate at 

 their inner extremities, the stronger branch turning backward 

 toward the occipital furrow, the smaller branch turning slightly 

 forward, between these two divisions of the furrow is a slight 

 node upon the side of the glabella. Occipital furrow arching 

 .forward in the center, rather broad and rounded in the bottom 

 in the middle, becoming narrower and more deeply impressed 

 back of the posterior glabellar lobes, extended as a broad pos- 

 terior cheek, furrow across the posterior portion of the cheeks. 

 Occipital segment broadest in the middle, becoming narrower 

 back of the posterior glabellar lobes. Cheeks strongly convex 

 with rounded, lateral, marginal borders, and sharp, posterior, 

 marginal borders. Just within the raised marginal borders 



