22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Hyolithcs billittysi Walcott (part), U. S. Geol. Surv. Bull. 30, p. 134, pi. 13, 

 figs. I, la-d, 1886; idem, loth Ann. Rep., p. 620, pi. 75, figs, i, la-d, 

 1891 ; Lesley (part), Geol. Surv. Pennsylvania, Rep. P4, p. 294, figs. 

 1889; Gr'Vbau and Shimer, N. A. Index Foss., vol. 2, p. 3, figs. i2iie-g, 

 1910. 



//. whitci i.s a rather small species with a thick shell. The pos- 

 terior side is nearly flat ; the anterior is angulated giving the tube a 

 nearly equilateral triangular outline. The lateral corners are rounded. 



Lower Cambrian, Pioche ; (loc. 31a) southeast of Pioche, High- 

 land Range, Nevada. 



Cotypes. — U.S.N.M. nos. 8579, 15377. 



Hyolithes poulseni, n. sp. 



Hyolithcs billingsi Poulsen, Aleddels. Gr^nland, vol. 70, p. 254, pi. 15, figs. 



26, 27, 1927. 

 HyoUthns (Hyolitlius) billingsi Poulsen, idem, vol. 87, no. 6, p. 22, pi. 3, 



fig. 6, 1932. 



This species has a flat posterior side and a rounded anterior face. 

 It expands much more rapidly and is larger than H. billingsi. The 

 anterior surface is striated. 



Lower Cambrian, Cape Kent ; Cape Kent, North Greenland. 

 Bastion ; Hyolithus Creek, East Greenland. 



Cotypes and plesiotypcs. — Min. Mus. Copenhagen ; plastotypes, 

 U.S.N.M. no. 70951. 



CRUSTACEA 

 STENOTHECA Salter, 1872 



Stcnotheca Hicks (Salter MSS.), Quart. Journ. Geol. Soc. London, vol. 28, 

 p. 180, 1872; Walcott, U. S. Geol. Surv. Bull. 30, p. 128, 1886; 

 Matthew, Trans. Roy. Soc. Canada, vol. 8, p. 132, 1891 ; Grabau and 

 Shimer, N. A. Index Foss., vol. 2, p. 373, 1910; Cobbold, Geol. Mag., 

 vol. 71, p. 463, 1934. 



IVatsoncUa Grabau, Occ. Pap. Boston Soc. Nat. Hist., vol. 4, p. 631, 1900. 



Stenothcca, a generic name attached to museum specimens, was 

 published without description in 1872. In 1886 Walcott described 

 the genus but quite clearly based his remarks on Helcionella ritgosa 

 and its allies. Consequently his descri])tion is that of the gastropod 

 genus Helcionella. More recently Cobbold restudied Salter's types 

 and presented a generic diagnosis. 



In 1891 Matthew recognized the crustacean characters of Steno- 

 thcca, in which he was followed by Grabau and Shimer. The latter, 

 however, assigned only gastropod species to the genus. Cobbold 

 assigns the genus to the Notostraca. 



