OLENELLUS AND OTHER GENERA OF MESONACID^ 319 



of Mount Bosworth, a little north of the Canadian Pacific Railway 

 track between Stephen and Hector, British Columbia. Fragments 

 of a large OlencUns, probably of this species, occur at the same 

 locality as Nos. 35h and 587, but at a horizon 400 to 600 feet below 

 the top of the Lower Cambrian. 



(35I) dark, bluish-gray limestone at the base of the Mount Whyte 

 formation; and (60c) calcareous sandstones of the upper 20 feet 

 of the St. Piran formation ; both on the south slope of Ptarmigan 

 Pass, at the head of the Corral Creek, 9 miles (14.4 km.) north- 

 northeast of Laggan on the Canadian Pacific Railway, Alberta. 



(58V) about 450 feet (137 m.) below the top of the Lower Cam- 

 brian in a brownish-gray sandstone forming No. i of the field section 

 of the St. Piran formation, in the amphitheater between Popes Peak 

 and Mount Whyte, 3 miles (4.8 km.) northwest of Lake Louise, 

 southeast of Laggan, on the Canadian Pacific Railway, Alberta. 



(58X) about 300 feet (91 m.) below the top of the Lower Cam- 

 brian in the sandstones of the St. Piran formation, just below the 

 big clifif on the east shoulder of Castle IMountain, north of Castle, 

 on the Canadian Pacific Railway, Alberta. 



OLENELLUS ? CLAYTONI, new species 



Plate 40, Figs, g-ii 



Olcncllus chytoni Walcott (in part), 1908, Smithsonian Misc. Coll., Vol. 

 53, No. 5, p. i8g. ( Name used in No. 6 of section. The specimens Hsted 

 include forms now referred to Olcncllus gilbcrti.) 



Of this species forty-eight specimens of the cephalon and two of 

 the hypostoma are in the collection. The cephalon is characterized 

 by having a glabella constricted at the third pair of furrows, from 

 whence it widens to the large, expanded anterior lobe. The palpe- 

 bral lobes are large and long like those of 0. thompsoni fpl. 34 1. 

 I was at first inclined to place 0. claytoni with 0. frciiioiifi [pi. 37], 

 but the shorter palpebral lobes and dififerent outline of the glabella 

 of the latter led me to separate the two forms. The outline of the 

 glabella is more like that of IVaiuicria 7valcotlani!s [pi. 30, fig. 2] 

 and small cephalon of ElUptochcphala asaphoides [pi. 24, fig. 6] , 

 but in specimens of the O. ? claytoni of the same size this similar- 

 ity is not present. 



A small cephalon 2 mm. in length has very strong connecting 

 ridges that merge into the expanded anterior lobe of the glabella 

 so that it appears much like the young cephalon of Olcncllus lap- 



