^°]'89o'"'] PROCEEDINGS OF THE NATIONAL MUSEUM. 275 



frontal limb ; palpebral lobes of medium size aud separated from tbe 

 cheek by a strong furrow; a short oblique ocular ridge crosses the dor- 

 sal furrow ; frontal limb shown only at the sides, as the glabella arches 

 down to the groove marking off the broad companulate frontal rim; the 

 latter extends forward to a blunt point and is nearly one-third the 

 entire length of the head. The associated free cheek has a broad mar- 

 gin and a relatively small trapezoidal-shaped body beneath the base of 

 the eye lobe. 



Surface of the glabella, fixed cheeks, and body of free cheeks strongly 

 pustulose; frontal and side margin smootli. 



That this species is not a true Ptychoparia is evident; it is so referred 

 with P. f pernasutus and other species, while awaiting a. revision of the 

 genera of American Cambrian trilobites. 



Formation and locality. — Upper Cambrian (Potsdam Terraue). Pack- 

 saddle Mountain, Llano County, Texas. Collector, C. D. W. 



Nat. Mus. Cat. Invert. Foss., 238G1. 



Ptychoparia vacuna sp. iiov. 

 Plate XXI, Figs. 8 and 12. 



The portions of the head preserved shows it to have been strongly 

 convex. Glabella slightly converging towards the broadly rounded 

 front; glabellar furrows slightly impressed, three in number on each 

 side, and extending obliquely inward nearly one-third the distance 

 across. Occipital furrow shallow, and arching forward at the center; 

 occipital segment narrow, arching forward aud with a small node at 

 the center. 



Fixed cheeks practically obsolete, except in their extension into the 

 long, posterolateral limbs; palpebral lobes unknown; frontal limb 

 very broad, sloping abruptly downward from the faint dorsal furrow in 

 front of the glabella to where it curves forward and merges into the 

 flattened frontal borders. Surface apparently smooth. 



Formation and locality. — Ui)per Cambrian (Potsdam Terrane) Lime- 

 stone in Spring Creek Canon, Black Hills, Dakota. Collected under 

 charge of Prof. F. B. Cari)enter. 



Nat. Mus. Cat. Invert. Foss., 23862. 



Ptychoparia (Liostracus) panope sp. nov. 

 Plate XXI, Fig. 13. 



Of the species we have only the portions within the facial sutures. 



Glabella convex, sides converging a very little towards the broadly 

 rounded front; glabellar furrows scarcely to be distinguished on the 

 smooth surface ; occipital furrow well defined and arched forward at the 

 center; occipital segment a little broader at the center than at the 

 sides, slightly convex and arched forward near the center; dorsal 

 groove distinct all about tlie glabella. 



