MOLLUSCA—CONULARIDA—TORELLELLID^. 7 



angle about 2°-5°. Older portion of tube is septate, the septa 

 convex backward. 



Lower Cambric of Massachusetts and Newfoundland. 



III. Helenia Walcott. 



Shell an elongate, narrow, flattened, curved tube ; transverse sec- 

 tion and aperture elliptical ; surface with transverse, concentric im- 

 bricating growth lines. Cambric. 



16. H. bella Walcott. (Fig. 12 17.) Cambric. 



Fig. 121 6. Hyolithes neapolis, X 7> X 

 1.5, X 7- (After Clarke.) 



Fig. 1217. Helenia bella. (After 

 Walcott. ) 



Curvature nearly semicircular ; cross section an elongated ellipse ; 

 apparently open at both ends; possibly referable to Dentaliidce. 

 Type of genus. 



Lower Cambric (Etcheminian) of Newfoundland. 



Family Torellellid^ Holm. 



IV. Hyolithellus Billings. 



Differs from Hyolithes in the slender elongated form of its 

 shell, the absence of a flattened face and especially in the star- 

 shaped arrangement of the numerous muscle markings on the in- 

 terior of the operculum. It likewise lacks the anterior lip and its 

 accompanying forward bending growth lines upon the dorsal side. 

 Cambric. 



17. H. micans Billings. (Fig. 1218, a-d.) Cambric. 



Shell long, very slender; apical angle about i°-2°. Transverse 

 section circular or broadly ovate. Type of genus. 



