PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. Ill, pp. 267-373. PLS. xxxi-xxxii July 13, 1901, 



A NEW SPECIES OF OLENELLUS FROM THE 



LOWER CAMBRIAN OF YORK COUNTY, 



PENNSYLVANIA. 



By Atreus Wanner. 



Reference is made by Mr. Charles D. Walcott, in Bulletin No. 

 134, United States Geological Survey, to the Olenellus fauna 

 of the York county, Pennsylvania, Cambrian. At that time 

 fragmentary impressions of trilobites had been collected, but no 

 locality had yielded specimens that could then be referred with 

 certainty to any described species of Olenellus. I have re- 

 cently found complete specimens of several species, one series 

 illustrating different stages of growth and presenting variable 

 features of Olenellus thompsoni. One new species of the sub- 

 genus Holmia is beautifully preserved and I take pleasure in 

 naming it after Mr. Walcott in recognition of his work on the 

 Cambrian faunas. 



OLENELLUS (HOLMIA) WALCOTTANUS sp. nov. 



(PI. XXXI, figs. I, 2; PI. XXXII, figs. I, 2, 3, 4.) 



General shape of entire specimen (PL xxxi, fig. i) ovate; width 

 about two-thirds of length. 



Transverse diameter of cephalic shield about twice the longitudinal ; 

 marginal furrow shallow ; rim of moderate and nearly uniform width, 

 being apparently narrowest in front of the glabella and terminating in 

 two postero-lateral spines. In all the specimens found, the anterior 

 part of the rim is obscured and evidently narrowed by the flattening 



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