NO. 24 PTARMIGANIA STRATA RESSER 51 



ALOKISTOCARIDAE, new family 



ALOKISTOCARE Lorenz, 1906 

 ALOKISTOCARE EUCHARE, n. sp. 



Plate 2, figs. 11, 12 



A single cranidium, in contrast with the great development in the 

 superjacent Spence shale represents the genus in the Ptarmigania 

 beds. It is typical in its proportions and relief. The glabella tapers 

 to a rounded front, which is separated from a medially swollen pregla- 

 bellar area by a deepened anterior dorsal furrow. The surface of 

 the glabella is not so well preserved, but the shallow furrows seem to 

 be rather wide. The glabella occupies about half the cranidial length. 

 At the eyes, which are rather small and situated behind the cranidial 

 midpoint, the fixigenes are about as wide as the glabella. The eye 

 lines are strong, arising near the anterior glabellar angles. The brim 

 is wide and generally concave, with the middle portion of the pre- 

 glabellar area considerably swollen. The outer third is upturned as 

 a flat rim. Back of the anterior furrow thus formed, a ridge crosses 

 the brim parallel to the anterior margin. Brim vertically striated. 



Locality 54s. 



Holotype.— U.S.N.M. No. 98544. 



ALOKISTOCARE EUZONA, n. sp. 

 Plate 12, figs. 4, 5 



A single cranidium represents this species, which seems to be 

 typical in its development. The glabella tapers forward at about the 

 average rate and several pairs of glabellar furrows are faintly indi- 

 cated by indentations near the dorsal furrow. The glabella is arched 

 above the dorsal furrow with moderate convexity. The glabella, 

 exclusive of the occipital ring, occupies about half the cranidial length. 

 The fixigenes are just about half the glabellar width and rise con- 

 siderably from the dorsal furrow. As usual the brim is wide and long, 

 because the anterior facial suture diverges. Next to the anterior dorsal 

 furrow the preglabellar area rises rather abruptly and then is gently 

 concave to the front margin. Because the anterior angles are de- 

 pressed, the slope of the preglabellar area becomes much steeper 

 toward the anterior angles. Eye lines present. Eyes of moderate size, 

 situated behind the midpoint of the glabella. No brim developed but 

 the doublure shows as the usual impression on the brim. Brim 

 vertically marked by anastomosing lines. 



A. euzona is closely allied to A. cucharc from Two Mile Canyon. 



Locality 59L 



Holotype.— U.S.N.M. No. 98545. 



