MARYLAND GEOLOGICAL SURVEY 359 



anterior margin of the head. Glabellar furrows well defined, but not 

 extending across the glabella. The two anterior pairs straight, each 

 portion extending over about one-fourth the width of the glabella. The 

 third pair extending inward about as far as the other two, and then 

 bending abruptly backward and joining the occipital furrow, leaving the 

 posterior glabellar lobes more or less detached. Occipital furrow deep 

 and well defined, arching a little forward upon the glabella extended 

 laterally upon the fixed cheeks nearly to the lateral margins, where it 

 joins a marginal furrow just in front of the genal spine, which passes 

 anteriorly. Occipital segment well defined. Dorsal furrow rather sharply 

 impressed. Fixed cheeks convex, their posterior lateral angles extended 

 into prominent, curved, genal spines. Whole surface of the head, except 

 the dorsal, glabellar, occipital and marginal furrows, strongly granulose 

 or papillose, with some scattered tubercles larger than the others." 

 Weller, 1903. 



The above description by Weller applies in detail to the characters of 

 the head fragments found in the Chambersburg limestone. Several 

 species have been confused under the name of Ceraurus pleurexanthemus 

 and better material may show the Chambersburg limestone specimens to 

 be incorrectly referred here. 



Occurrence. CHAMBERSBURG LIMESTONE ( Caryocystites bed). Fort 

 Loudon, Franklin County, Pennsylvania. Black Eiver of New York, 

 Canada, etc. 



Collections. Maryland Geological Survey, TJ. S. National Museum. 



Genus PLIOMEROPS Raymond 



PLIOMEROPS SALTERI (Billings) 



Plate XXXVI, Fig. 13 



Amphion salteri Billings, 1861, Canadian Nat. and Geol., p. 322, text fig. 6. 

 AmpMon salteri Billings, 1865, Pal. Foss., vol. i, Geol. Surv. Canada, p. 352, 

 text fig. 339. 



Description. Pygidium small, about 6 mm. long and 10 mm. wide at 

 the base. Glabella convex, oblong, one-third the width of the head, with 



