38 LOWER CAMBRIAN FOSSILS WALCOTT. 



elliptical. Dorsal face slightly convex and carving gently from the ex- 

 tremity to the anterior subspatulate portion. Ventral face strongly 

 and regularly convex transversely; the dorsal and ventral faces meet 

 to form the rounded lateral angles of the shell. Aperture oblique, the 

 margin extending on the dorsal side ; the peristome of the ventral side 

 is slightly curved backward. Operculum unknown. Shell thick and 

 strong. 



Surface of the shell transversely or concentrically striated; on the 

 dorsal surface the striae are faintly defined and on the ventral surface 

 strongly marked and also cancellated by raised lines with finer strke 

 between. 



The largest specimen collected has a width of 16 mm at the aperture 

 and a length of about 55 mm is indicated, the portion preserved being 

 48" ,m in length. 



I do not know of any identical species, although the surface mark- 

 ings are like those of HyoHtlies nobilis Barraude.* 



The presence of a septum near the extremity of the shell is very dis- 

 tinct in one species where the point is broken off. 



Formation and locality. — Lower Cambrian. This species is found 

 in irregular masses of limestone resting on and among the bowlders of 

 gneiss forming the base of the Olenellus zone on Manuel's Brook, Con- 

 ception Bay, Newfoundland. 



Nat. Mus. Cat. Iuvt. Foss., No. 18319. 



Hyolithes similis sp. nov. 



Form an elongate subtriangular pyramid, gradually and regularly 

 tapering to an acute extremity. The angle of tapering of the dorsal 

 side is about 13°. Transverse section subtriangular. The ventral 

 angle is sharp and the lateral angles rouuded. Dorsal face slightly 

 arched longitudinally, transversely nearly flat, except at the sides, 

 where it curves slightly to meet the two planes of the ventral face, 

 which is strongly angular at the center. Aperture oblique; the peri- 

 stome is indented at the center of the ventral side and arched over the 

 subspatulate exteusion of the dorsal face. Operculum unknown. Shell 

 comparatively thin. 



Surface of the shell marked by transverse or concentric striae that 

 arch forward on the dorsal face. The ventral face is further marked 

 by four raised lines on each side of the central angle, and between the 

 raised lines by very fine longitudinal striae. 



The portion preserved of the largest specimen collected has a length 

 of 43 mm . When entire it was about 50 mm in length ; it has a width at 

 the aperture of 13 min , and a depth of 7""". 



In general form this shell is closely related to E. americanas. It dif- 

 fers in the strongly marked ventral surface. 



Formation and locality. — Same as H. tevranovicus. 



Nat. Mus. Cat. Invt. Foss., No. 18317. 



* Syst. Sil. Boheme, Vol. in, 18G7, pi. 13, figs 22-26. 



