PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 337 
Flattish orthoids are fairly common in the Table Head series and in boulders 
of the Mystic conglomerate. It is likely that other species of Hesperonomiella 
will be recognized among them. 
Genus HESPERONOMIELLA Ulrich and Cooper, 1936 
Hesperonomiella Utricu and Cooper, Journ. Paleont., vol. 10, No. 7, p. 622, 1936; Geol. Soc. 
Amer. Special Pap. 13, p. 123, 1938. 
HESPERONOMIELLA MINOR (Walcott) 
Plate 121, H, figures 20-22 
This is a poorly known genus and species. The interiors have hitherto been 
known only from molds of the interior produced by burning off the shell. Re- 
cently a few excellent interiors of both valves were obtained from L. F. Hintze. 
These show the pedicle valve to have a shallow delthyrial cavity and probably 
short, stout dental plates. These structures if present are concealed by shell de- 
posited on the sides of the delthyrial cavity. The teeth are so large that they 
seem to rest on the floor of the delthyrial cavity. Pallial marks are strongly 
developed and consist of strong vascula media extending anterior of the diductor 
scars and dividing at about two-thirds the distance from the beak. The brachial 
valve has short and stout brachiophores much concealed by excess shell of the 
notothyrial platform. 
Hypotype.—117939. 
Horizon and locality—Upper part of Pogonip group= Wahwah formation in 
Utah: T. 22 S., R. 14 W., Confusion Range, Millard County. 
HESPERONOMIELLA QUEBECENSIS Cooper, new species 
Plate 172, D, figures 13-20 
Shell of about the usual size for the genus, wider than long; cardinal extremi- 
ties acute; hinge forming the widest part of the shell; lateral margins gently 
rounded; anterior margin broadly rounded; surface multicostellate but orna- 
mentation too poorly preserved to describe accurately. 
Pedicle valve gently convex in lateral profile and broadly convex in anterior 
profile. Umbo and median regions somewhat swollen; lateral slopes concave, 
short, gentle; anterior slope short and gentle; delthyrial cavity narrow, triangu- 
lar ; vascula media strongly developed. 
Brachial valve very gently convex in lateral profile; nearly flat in anterior 
profile; umbonal region gently swollen; sulcus shallow and broad, extending to 
the anterior margin ; flanks on each side of sulcus gently swollen. Brachiophores 
short ; median ridge low, short. 
Measurements in mm.— 
Hinge 
Length Midwidth width Thickness 
TANGEIDE ie dle safe 2c << 3 ae'se = sakes « 14.1 17.6 17.6-+ rey 
Paratype (pedicle valve 116849d)... 14.6 17.8 21.0 17 
% (brachial valve 116849b). 10.5 15.8 17.0 ? 
