36 PROCEEDINGS OF THE NATIONAL MUSEUM. ' vol. xxix. 



curv^es backward slightly at the sides and then arches gently forward 

 at the middle; occipital ring of medium width, curving slightly back- 

 ward at the ends and forward at the center, rounded on top; dorsal 

 furrow strongly marked all about the glabella, and passing posteriorly 

 into a narrow but well-dehned furrow within the posterior margin of 

 the postero-lateral limb; the front of the glabella almost overhangs a 

 strong furrow within the frontal border that separates the frontal 

 border from the fixed cheeks; frontal border or rim strong, rounded, 

 and arching slightly upward in front of the glabella. 



Fixed cheeks a little more than one-half the width of the glabella. 

 They slope gently back to the furrow^ on the postero-lateral limb and 

 rather rapidly downward in front of the palpebral lobe to the furrow 

 within the frontal border. A clearh^ defined, low, rounded ocular ridge 

 extends opposite the anterior fourth of the glabella to the palpebral 

 lobe, into the rim of which it merges; postero-lateral limb about one 

 and one-third times as long as the width of the glabella at its base, and 

 back of the palpebral lobe about one-third the length of the head; 

 palpebral lobe a little less than one-third the length of the head, ele- 

 vated at the outer rim, and rather narrow. 



The facial sutures cut through the rounded frontal margin of the 

 head obliquely and around backward, passing almost directly to the 

 anterior margin of the palpebral lobe; curving around the rather 

 small ej^e lobe, they pass obliquely outward and backward, cutting 

 the border of the head a little in advance of the postero-lateral angle. 



Free cheeks roughly subtriangular, with the outer margin bordered 

 by a thickened, rounded rim, which graduall}^ increases in width to 

 the base of the long postero-lateral spine. Back of the spine to the 

 facial suture the border narrows rapidly. The body of the cheek 

 rises at a uniform slope to the base of the eye lobe. 



Thorax with a convex axis that narrows gradually from the anterior 

 segment, where the width is 15 mm., to the twelfth segment, where it 

 is 12 mm. One specimen preserves twelve segments, with the pygi- 

 dium, and it may be that other segments are broken off. The segments 

 are nearly transverse, except at the geniculation on the pleural lobes, 

 where the falcate extremities bend slightly backward; pleural lobes 

 flattened three-fourths of the distance out, where the}" curve slightly 

 downward to the extremities of the pleurae; pleural groove occupying 

 nearly the entire width of the pleura, except near the axis, where it 

 narrows toward the front margin. At the outer extremity it fades 

 out where the pleura curves outward and backward. There is some 

 difference in the strength and width of the pleural groove in different 

 specimens. In some it has practically the same width from the axis 

 out to its extremity, while in others it is narrow toward the axis and 

 not quite as broad through the central portions, 



Pygidium large, semicircular; axial lobe divided by four well- 



