are distinct at the sides, but do not extend entirely across the 

 glabella except in very faint depressions; the anterior furrows 

 •are deep, very distinct, situated a little anterior to the eyes, 

 extending each about one-third across the glabella, and giving 

 to the frontal lobe a transversely elliptical outline. 



The occipital ring is narrow, ornamented on the middle by 

 a single, short, sharp spine. Eyes very prominent; short 

 reniform, containing about thirty-five vertical ranges of lenses, 

 the middle ones of which have nine each. Cheeks small, 

 prominent on the anterior portion; marked near the posterior 

 margin by a deep groove, the continuation of the occipital 

 furrow. Thoracic segments unknown. 



Pygidium somewhat elongate triangular, extended posteriorly 

 into an accute spine; central lobe or axis marked by ten or 

 twelve narrow rings; the lateral lobes less prominent, marked 

 bj ten flattened ribs, which terminate in a narrow, flattened 

 margin ; eight of these ribs are double throughout their entire 

 length; the posterior ones are directed obliquely backwards. 



This species somewhat resembles D. Jimuluris, (Phacops 

 limuluris, Pal. N. Y., PI. 67, fig. 1); but differs in the propor- 

 tionally larger glabella, the larger and more prominent eyes, 

 and the extension of the anterior border; the pygidium is less 

 rounded on the anterior margin, the spine is more obtuse, the 

 flattened margin outside of the ribs is narrower, and the num- 

 ber of ribs on the lateral lobes is greater. 



Geological Formation and Locality. In Niagara limestone, 

 at Waukesha. 



Collectors. I. A. LapJiam, T. J. Hale^ James JV. Hall. 



Errata. — In this report, particularly in the first sixteen pages, will be 

 found many typographical and other errors, which have occurred through 

 the want of a competent proof reader. 



MCZ ERNST MAYR LIBRARY 



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