348 New Species of Trilohite from the Trenton Limestone. 



Movable cheeks ; upper margin forms the base of the eye ; anteri- 

 orly an acr.te angle terminating under the anterior base of the eye ; 

 posterior margin with two spines ; the inner short, sharp pointed, 

 curves downward and backward on a line with the pleura of the first 

 segment of the thorax ; outer spine long, nearly flat, obliquely striated, 

 terminates opposite the axial lobe of the fifth segment. 



At the anterior base, of the eyes the outer margin of the movable 

 cheeks curve abruptly downward and under forming a doublure, which 

 extends around under the anterior margin of the glabella, and back- 

 ward under the cheeks to a line with the neck segment. 



Eyes large, elongated, depressed, occupy the curved space between 

 the upj)8r margins of the cheeks and the lateral margins of the 

 glabella : perpendicular in hight to each, surface finely reticulated. 



Facial sutures cutting the neck segment on a line with the base of 

 the eyes, extend obliquely up to the posterior lateral angles of the 

 glabella; curve outward around the top of the eyes, then abruptly 

 down forming their anterior margin, curving forward and slightly 

 upvv'ard they unite in front of the glabella. 



Hypostoma ; body quadrate, buccal margin produced into two long 



tapering lobes^ with a deep buccal notch between them ; upon the 

 ventral surface four elevated lines run the length of each lobe, two 

 central and one on each margin, the marginal lines of the outer 

 margins continue to the anterior margin of the body, three short 

 lines separating them near the autei'ior margin ; muscular scars 

 slightly elevated, oval, situated anterior to the buccal notch, they 

 are crossed by minute inosculating lines. Interior or dorsal sur- 

 face of the body cut away anteriorly forming a semi-circular depres- 

 sion, showing the intei'ior of the ventral surface, and muscular scars as 

 slight depressions crossed by minute strise ; ventral surface minutely 

 tubercular, interior surface smooth. The hypostoma was attached 

 to the doublure beneath the glabella ; the extremities of the buccal 

 lobes extending back to the anterior, edge of the seventh thoracic 

 segment. 



Thorax with ten segments arching forward, narrows rapidly to the 

 pygidium ; axial lobe separated from the plural lobes, by a sharp ridge 

 extending two-thirds the distance across each segment, a slight 

 diagonal furrow crosses the segments of the axial lobe near the junc- 

 tion of the axial and plural lobes. Plurae flat, curving dovi'u one- 

 half the way outward where they are reflected backward, terminating 

 in short pointed extremities. 



Pygidium small, subquadrate, posterior margin narrowing is divided 



