OLENELLUS AND OTHER GENERA OF MESONACID.T: 3OI 



(60b) compact sandstones of St. Piran formation about 2,000 

 feet (610 m.) below the Mount Whyte formation and 200 to 300 

 feet (61-91 m.) above the Lake Louise shale, at Vermilion Pass, 

 on the Continental Divide between British Columbia and Alberta, 

 west-southwest of Castle on the Canadian Pacific Railway, Alberta, 

 Canada. 



WANNERIA HALLI, new species 

 Plate 31, Figs, i-ii 



The cephalon, hypostoma, and fragments of the thoracic seg- 

 ments of this species are all that is known of it. The cephalon [pi. 

 31] has the same general outline and broad marginal border as that 

 of W. zmlcottanus [pi. 30, figs, i and 2]. The cephalon of W. halli 

 differs from that of the latter species in having a more narrow gla- 

 bella in proportion to the width of the cheeks and a smaller anterior 

 lobe. The genal angles of 27 specimens of the cephalon of JV. halli 

 are all advanced in the adult, and only in the young are they on a 

 Hne with the posterior margin [figs. 5 and 6]. In the larger speci- 

 mens [figs. I and 3] the intergenal angle is a right angle ; this grad- 

 ually changes as the cephalon grows smaller [figs. 2, 4, and 6] 

 until the genal angles slope inward [figs. 5 and 7] and rest against 

 the intergenal spines [fig. 8]. 



The palpebral lobe of the adult [fig. 3] is relatively small, less 

 than one-third of the length of the cephalon, but with decrease in 

 size of the cephalon the lobe increases in length [figs, i, 2, 4, 7, and 

 8] until in the smallest cephalon [fig. 8] it is seven-twelfths of its 

 length ; this includes the strong, elevated ridge that unites the lobe 

 with the anterior lobe of the glabella. The narrowing of the glabella 

 at the posterior end of the anterior lobe is also a very striking feature 

 of the young of W. halli [figs. 5, 7, and 8]. 



The associated h3'postoma has an elongate oval body that narrows 

 posteriorly to the neck, that connects it with the convex transverse 

 posterior section. A deep, oblique, lateral furrow separates the body 

 on each side from the narrow raised outer rim and the posterior 

 section ; the outer rim merges into the convex posterior section that 

 arches about the posterior portion of the body and the posterior and 

 lateral margins are bordered by a flattened margin that is perforated 

 by twelve small, round holes that, when the outer edge is broken 

 away, leave the interspaces as blunt points which form a denticulated 

 margin. The perforated margin occurs on very small specimens and 

 those up to 2 mm. in length. Larger specimens have a denticulated 



