24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



Stenotheca crosbyi (Grabau) 



Watsonella crosbyi Grabau, Occ. Pap. Boston Soc. Nat. Hist., vol. 4, p. 632, 

 pi. 31, figs. Qa-f, 1900. 



Lower Cambrian, Weymouth ; Pleasant Beach and Sandy Cove, 

 Cohasset, Massachusetts. 



Cotypcs. — Boston Soc. Nat. Hist. nos. 11951-11954. 



STENOTHECOIDES, n. gen. 



Stciwthecoides is related to Stenotheca, but is much narrower and 

 longer, with, a relatively wider aperture. The genus is characterized 

 by the long narrow carapace which is curved longitudinally. This 

 curvature is usually much greater in cross-section, amounting to a 

 fold along the apex. The apertural outline increases from the narrow 

 anterior end almost evenly to a broadly rounded rear margin. The 

 marginal outline of some species is not bilaterally symmetrical, curv- 

 ing out more on one side than the other. The surface is marked with 

 growth lines surrounding the anterior end, each extending itself rear- 

 ward at a greater rate, so that while the anterior ends remain close 

 together, the lines become longer and longer, reaching to the posterior 

 portion of the test. 



Genotype. — Stenotheca elongata Walcott. 



Stenothecoides elongata (Walcott) 



Stenotheca elongata Walcott, U. S. Geol. Surv. Mon. 8, p. 23, pi. q, figs. 2, 

 2a, 1884; idem (part). Bull. 30, p. 129, pi. 12, figs. 4a, b, 1886 (not fig. 

 4^5*. tahradorica ) . 



Helcionella elongata Walcott, Smithsonian Misc. Coll., vol. 67, no. 3, p. 63, 

 1917. 



Middle Cambrian, Eldorado; (loc. 55b) West slope Prospect Peak, 

 Eureka District, Nevada. 



Holotype.—U.S.'NM. no. 15364. 



Stenothecoides labradorica, n. sp. 



Stenotheca elongata Walcott (part), U. S. Geol. Surv. Bull. 30, p. 129, 

 pi. 12, fig. 4, 1886. 



This species was identified with that from the Eureka District, 

 Nevada, but the drawing shows that it is clearly distinct. S. labra- 

 dorica is shorter and wider and the apertural margin evidently is not 

 as symmetrical as S. elongata. The growth lines are also somewhat 

 weaker. 



Lower Cambrian, Forteau ; L'Anse au Loup, Labrador. 



Holotype.—U.S.'^.M. no. 14883. 



