276 NEW UPPER CAMBRIAN FOSSILS WALCOTT. 



Fixed cheeks of medium width ; palpebral lobes rather loug, narrow, 

 and separated from the cheeks by a narrow and distinctly marked 

 groove; a narrow ocular ridge crosses the cheek from the palpebral 

 lobe to the dorsal furrow. 



Frontal limb of medium length and bent downward from tbe dorsal 

 suture to where it curves outward and merges into tbe flattened border. 

 Surface smooth. 



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

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

 charge of Prof. F. B. Carpenter. 



Nat. Mus. Cat. Invert. Foss., 2385G. 



Agraulos saratogeusis sp. nov. 



Plate XXI, Fig. 14. 



Bathyurus armatiis Walcott, 1879, 32tl Rep. State Mns. Nat. Hist. New York, p. 131. 

 Ptijchoparia (A.) sarafogensis Walcott, 1»86, Bull. U. S. Geol. Survey, No. 30, p. 21. 

 (Name used only iu list.) 



Head convex, slightly semi-subelliptical in outline, and terminating 

 in round, short, postero-lateral spines. 



Glabella moderately convex, truncato conical, sides converging 

 slightly towards the broadly rounded front, about one sixth longer than 

 wide; marked by two pairs of slightly indented glabellar furrows that 

 extend inward with a slight backward obliquity; on the casts of the 

 interior of the larger specimens the furrows are scarcely to be seen ; 

 occipital furrow well defined and arched forward at the center; occip- 

 ital segment rising to a short, blunt spine at the center and narrowing 

 towards the sides; dorsal furrow well defined about the glabella. 



Fixed cheeks narrow, anteriorly they merge into the broad rounded 

 frontal limb, and posteriorly into the short postero lateral limbs; pal- 

 pebral loijes small and situated a little in front of the transverse center 

 of the head. The frontal limb about one-fourth the length of the head 

 and curved down to the margin without any intervening furrow. 



Free cheeks convex and somewhat tumid, irregularly triangular in 

 outline and without a marginal border. Thff associated pygidium is 

 convex, strongly lobed and without a distinct marginal furrow. Axial 

 lobe intermarginal, convex, and divided into four annulations and an 

 anterior doublure by four distinct transverse furrows ; lateral lobes 

 crossed by three main furrows and two shorter ones, corresponding to 

 the furrow on the lateral lobe of the thoracic segments, .thus outlining 

 three anchylosed segments in the pygidium ; a fourth segment and the 

 terminal portion are also outlined by a very faint ridge. 



Thorax unknown. 



This is a very distinctly marked species allied to Bathyurus arniatus 

 Billings.* 



* Pal. Fobs., vol. 1, 1865, p. 411. 



