NO. 9 NEW YORK POTSDAM-HOYT FAUNA 2/3 



Observations. — This very striking- form is represented by numer- 

 ous specimens of the cranidium with a few free cheeks and pygidia 

 referred to it. The most nearly related species is Ptychaspis granu- 

 losa (Owen), which differs in having a proportionately shorter, more 

 convex cranidium and smaller palpebral lobes. The pygidium (fig. 

 i8) is very doubtfully referred to the species. The generic reference 

 is somewhat doubtful as the large palpebral lobes and broadly 

 rounded anterior margin of the glabella suggest Dicellocephalus 

 lodensis (Whitfield). 



Formation and locality. — Upper Cambrian, Hoyt limestone: (76) 

 Arenaceous limestone at Hoyts quarry 4 miles (6.4 km.) west of Sara- 

 toga Springs; and (76a) in a railroad quarry, i mile (1.6 km.) north 

 of Saratoga Springs ; both in Saratoga County, New York. 



A form apparently identical with P. speciosus was found in a drift 

 block of sandstone, near Trenton Falls, Oneida County, New York, 

 supposed to have been derived from the Potsdam sandstone west of 

 the Adirondack IMountains. 



Genus DICELLOCEPHALUS Owen 

 DICELLOCEPHALUS HARTTI (Walcott) 



Plate 44, figs. i-7a. 



Conocephalites hartli W.\lcott, 1879, Thirty-second Ann. Rept. New York 



State Museum, p. 130. (Original description of species.) 

 Dicellocephalus hartti Walcott, 1886, Bull. U. S. Geol. Surv., No. 30, p. 21. 



(Name used in list of species.) 

 Dicellocephalus hartti (Walcott), Lesley, 1889, Geol. Surv. Pennsylvania, 



Rept. P4, Dictionary of Fossils, Vol. i, p. 199. (Text figure reproduced 



from drawing sent him by Walcott.) 



Glabella truncato-conical, moderately convex ; width at base, ex- 

 cluding occipital segment, equal to the length ; slightly rounded in 

 front, with anterior lateral angles abruptly rounded ; posterior glabel- 

 lar furrow extends obliquely in about one-third the distance across 

 the glabella from each side, where it is united by a transverse furrow ; 

 middle furrow extends obliquely in from each side, but is not united 

 at the center ; anterior furrow obscurely defined opposite the anterior 

 angle of the palpebral lobe. Occipital furrow broad and not deeply 

 impressed. Occipital ring broad and slightly convex. Dorsal furrow 

 well defined at the sides and front. 



The facial suture curves slightly outward from the frontal margin, 

 thence curving in to the anterior angle of the palpebral lobe, passes 

 to the posterior angle of the palpebral lobe, and thence obliquely 

 outward to the margin of the posterior limb. 



