MOLLUSCA—CONULARIDA—HYOLITHID^. 



5 



less convex than ventral. In addition to the growth lines which 

 cover the entire shell the ventral surface is marked by strong lon- 

 gitudinal raised lines with finer striae between. 



Lower Cambric of Conception Bay, Newfoundland. 



9. H. decipiens Matthew. (Fig. 1214, a-c.) Cambric. 

 Apical angle 15°. Transverse section of shell subtriangular. 



Surface marked only with the concentric growth lines. 



Middle Cambric St. John group (Protolenus beds) of New 

 Brunswick. 



10. H. acadicus Hartt. (Fig. 1214, (/.) Cambric. 



<z? 



Fig. 1214. a-c, Hyolithes decipiens, enlarged, with section. (After Matthew.) d, 

 H. acadicus ; e, H. danianus ; f, g, Orthotheca emmonsi and section. ( After Walcott. ) 



Transverse section subtriangular, about twice as wide as high. 

 The forward projecting anterior margin semicircular. Surface 

 of shell with concentric growth lines and microscopic longitudinal 

 striae. 



Middle Cambric St. John formation of New Brunswick. 



11. H. danianus Matthew. (Fig. 1214, ^.) Cambric. 

 Transverse section semielliptical ; surface of the curved shell 



with concentric growth undulations. 



Middle Cambric St. John formation of New Brunswick. 



12. H. shaleri Walcott. (Fig. 1215.) Cambric. 

 Large shell with dorsal face the least convex transversely and 



«^lightly convex longitudinally, the growth lines arch forward form- 



