390 The Ohio Journal of Science [Vol. XIX, No. 7, 



Proetus collinodosus, sp. nov. 

 Plate XVIII, Figs. 7 A, B. 



Cranidium 10 mm. in length along the middle; of this length 7 mm. 

 is occupied by the glabella, 1.7 mm. by the anterior border, and 1.3 mm. 

 by the neck-ring. The anterior part of the glabella is in contact with 

 the furrow which outlines the inner margin of the anterior border of the 

 cranidium, and, when viewed directly from above, appears to encroach 

 slightly upon the posterior margin of this border. Posteriorly the glabella 

 has a width of 7 mm., and its general outline is oval-triangular, the sides 

 converging anteriorly at an angle of about 40 degrees. Along its anterior 

 margin the glabella is relatively narrow and opposite the anterior margin 

 of the palpebral lobes the sides of the glabella tend to be slightly con- 

 cave. The palpebral lobe appears to be 3 mm. in length and, at its 

 widest part, it diverges only 1.5 mm. from the glabellar furrow. The 

 posterior border of the glabella is strongly defined. The neck-ring 

 is comparatively flat for the greater part of its width, and bears a 

 minute tubercle at its middle. Laterally, the ends of this neck-ring 

 curve forward and are nodosely elevated, forming rather conspicuous 

 occipital lobes. These lobes are obliquely elliptical, about one and a 

 half millimeters in maximum wddth, and are distinctly delimited from 

 the remainder of the neck-ring. 



A dissociated free cheek shows the same broad marginal border, and a 

 genal spine similar in size and form to that of other species of this 

 genus. 



A dissociated pygidium is 4.5 mm. in length and S mm. in width. 

 The posterior part of the axial lobe is about one millimeter distant from 

 the margin of the pygidium. This axial lobe is marked b}^ 6 or 7 fairly 

 distinct rings but there is sufficient room posteriorly to admit of a total 

 of 8 rings. The pleural ribs are indistinctly defined, at least in the 

 only specimen at hand. 



Locality and Position: In the Holophragma zone, at the 

 top of the upper or Lilley division of the West Union formation, 

 in the Zink or Corporation quarry, in the eastern part of Hills- 

 boro, Ohio. 



Remarks: From Proetus determinatus Foerste, from the 

 Brassfield formation of Ohio, this species is distinguished 

 readily by the more triangular' outline of its glabella, and by 

 the close approach of the anterior part of the glabella to the 

 posterior part of the broad marginal border of the cranidium, 

 only a narrow groove separating the two. 



Proetus pachydermatus Barret, from the Helderbergian of 

 New Jersey and Maryland, also has tw^o lateral lobes belonging 

 to the neck ring, but the marginal border of the cranidium is 

 farther removed from the anterior outline of the glabella, and 



