46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



ARAPAHOIA ALBERTENSIS, new species 

 Plate 7, Figures 27-31 



This is a very abundant species and is normal for the genus. Its 

 outstanding characteristic is the enormous posterolateral limbs, which 

 have pushed the rear facial suture forward nearly to the front margin 

 of the glabella. In exfoliated specimens the glabella is clearly marked 

 by four pairs of glabellar furrows. The shallow occipital furrow 

 marks off a triangular neck ring extending into a long occipital spine. 

 A tubercle near its base seems to be a median eye. Anterior facial 

 suture diverges very little and evidently is intermarginal nearly to 

 the center. The libragene assigned to the species is short and stout, 

 to fit with the contour »f the facial suture. The pygidium assigned to 

 the species is also short and has a well-defined border. 



Sullivan formation; (loc. 64h) East Lyell Glacier, 48 miles north- 

 west of Lake Louise, Alberta. 



Ilolotypc. — U.S.N.M. No. 108705a; paratypes, Nos. 108705b, e. 



ARAPAHOIA PROLIXA, new species 



Plate 7, Figures 20-26 



This large species is represented by a number of specimens. In 

 length it resembles A. clongata. On exfoliated specimens the glabella 

 is clearly defined and shows faint traces of glabellar furrows. The 

 outer test has a keel. At the anterior end of the eye the fixigenes are 

 narrow, measuring a little more than the width of the dorsal furrow. 

 Anterior to the eyes the suture diverges, but less than in A. elongata. 

 In cross section the species has low convexity, attained by an even 

 curvature. Longitudinally it has greater convexity but this is also 

 attained with even curvature. Concentric lines appear just behind the 

 midpoint of the cranidium and possibly surround an eye. On the other 

 hand, the brim is characterized by vertical anastomosing lines, which 

 are stronger on exfoliated specimens. Unfortunately no examples are 

 complete but a rather wide libragene seems to represent the species. 

 The pygidium assigned to the species is convex, with a fairly well- 

 defined border. It has definite pleural furrows and grooves. 



Sullivan formation ; (loc. 64h) East Lyell Glacier, 48 miles north- 

 west of Lake Louise, Alberta. 



Holotype. — U.S.N.M. No. ■108704a: i)aratypes. Nos. io8704b-d. 



ARAPAHOIA WALCOTTAE, new species 

 Plate 7, Figures 12-14 



This is a short form similar to A. albertensis. In cranidia that 

 retain the test the outline of the glabella is indicated by a shallow 



