34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



with increasing curvature toward the rear. In cross section the 

 cranidium is convex, but the cheeks are nearly flat, sloping a little 

 downward from the dorsal furrow. Longitudinally the species is 

 very convex with the posterolateral limbs depressed and curved down 

 at their distal ends, and the anterior part of cranidium sloping down at 

 almost right angles to the rear portion. The anterior fixigenes form 

 a flange about twice as wide as the flat concave rim. Libragenes 

 unknown. Several specimens retain thoracic segments, one of them 

 as many as seven, which is possibly the total number. The pygidium 

 is characterized by a prominent axis in which four rings are traceable, 

 the first one being thickened and bearing a large axial spine. Four 

 pairs of faint pleural furrows end in pits inside the border. A thick- 

 ening along the rear margin delimits the first segment on the pleural 

 lobes. The four marginal spines evidently increase in size from the 

 front toward the rear. Surface marked by scattered granules on 

 elevated portions. 



Locality 59c 54s. 



Holotype and paratopes. — U.S.N.M. Nos. 985i8a-e. 



DOLICHOMETOPSIS PROPINQUA, n. sp. 



Plate 5, figs. 11-13 



This species is characterized by a long expanding glabella, which 

 is narrowest at the second pair of furrows. The furrows are all 

 shallow. The palpebral lobes are about half the glabellar width at 

 the same point, and anterior to the eyes the fixigenes form a flange 

 about three times the width of the rim. The eyes are long and not 

 greatly bowed, except toward the rear. Rim narrow in front, widen- 

 ing toward the anterior angles to meet the flange. Eye lines present. 

 The pygidium assigned to the species has a high axis, which termi- 

 nates very abruptly in the rear and the pleura are fairly well indicated 

 in the lobes. The four marginal spines increase only slightly in size 

 toward the rear. Surface nearly smooth, but with scattered 

 granulations. 



Locality 54s. 



Holotype and paratypc. — U.S.N.M. Nos. 98508a, b. 



DOLICHOMETOPSIS GREGALIS, n. sp. 



Plate 6, figs. 1-4 



This species is close to D. poulseni, with which it is associated. It 

 is characterized by its large size and a practically parallel-sided 



