50 Annals of the Carnegie Museum. 



In 1905 Messrs. Douglass and Raymond collected a large number of 

 cranidia and free cheeks of a Basilicas from the "buff" limestone about 

 20 feet above the top of the St. Peter sandstone on Straight River, two 

 miles south of Faribault, Minnesota. Associated with these portions of 

 head shields were a couple of fragmentary pygidia which appear to agree 

 w'th the description of Ptychopyge ulr'.chi Clarke. Comp ir ng these speci- 

 mens with those from the Black River of New York and Canada, we are 

 unable to find differences of specific value. Ptychopyge ulrichi was de- 

 scribed from pygidia, the axial lobes of which bore eight or nine annula- 

 tions, only three or four of which were well defined, and on the pleura 

 were five pairs of ribs and a trace of a sixth, two or three more showing 

 on the cast. This corresponds exactly with the specimens from New York 

 and Canada. 



Walcott states that Asaphns wisconsensis differs from A. romingeri 

 "by having a wider and less concave margin, with the glabella more 

 convex and subquadrate in front." These variations are noticeable on 

 the specimens from Ottawa and those from Minnesota, but it is always 

 the small specimens which have the wide margin and the more convex 

 glabella, so that these are probably characters of immaturity. While 

 we have not seen the types, we are inclined to believe that the two names 

 represent the same species. 



Description. 



Specimens from Ottawa. — Cranidium con\ex, expanded in front of the 

 eyes, concave around the anterior margin. Glabella prominent, definitely 

 outlined, constricted between the eyes, marked by a pair of diagonal 

 glabellar furrows between the eyes and obscure basal lobe back of the eyes. 

 Neck-ring narrow and convex, neck-furrow shallow. Just in front of the 

 furrow is a prominent median tubercle. From the front of the glabella 

 a low ridge crosses the concave border and ends in a blunt point on the 

 margin. Palpebral lobes large. The whole surface of the test is covered 

 with fine irregular striations. In young specimens the concave border is 

 proportionally broader, the anterior portion of the glabella more tumid, 

 and the glabellar furrows more deeply impressed than in mature ones. 

 The pygidia are nearly semicircular, with wide concave borders. Axial 

 lobe prominent, showing about eleven rings on the cast of a young speci- 

 men and seven on a larger one. On the pleura are five or six pairs of 

 prominent ribs. 



Specimens from New York. — A single pygidium was collected by Mr. 



