NOTES ON THE FOSSILS OF ONTARIO. 



143 



91. Pentamerus occidentalis, Hall. Guelph Formation, Hes- 

 peler, Guelpli and Elora. 



92. Trimerella grandis, Billings. Guelph Formation, Hespeler. 



93. Trimerella ACUMINATA, "Billings. Guelph Formation, Hespeler. 



94. DiNOBOLUS Galtensis, Billings. Guelph Formation, Hespeler. 



95. DiNOBOLUs, sp. Casts of a Dinoholus which is clearly distinct 

 from the preceding occur at Hespeler and Elora in the Guelph For- 

 mation. 



96. Megalomus Canadensis, Hall. {Eef. Pal. N.Y., Vol. II., pi. 

 Ixxx. figs, la-e, pL.lxxxi. figs, \ar-f, and pi. Ixxxii. figs. \a-i.) Casts 

 of this singular shell are not very rare in the Guelph Formation at 

 Hespeler, Guelph, Gait and Elora. 



97. Megalomus compressus, Nicholson and Hinde. Shell equi- 

 valve, valves compressed, the depth of both valves being little more 

 than one-third of the width. Form elliptical, the length nearly one- 

 third greater than the width. Umbones anterior, incrassated, with 

 apparently one cardinal and two lateral teeth. A single, deep, con- 

 centrically-striated muscular impression placed just in front of and 

 beneath the umbones, with a small circular pit above it. Pallial 

 line simple. Surface of the shell unknown. 



Fig. 6. — Megalomtis compressus, Nich. and Hinde. A, Side view of the cast of 

 the shell, natural size. B, The same viewed from above, ad, Cast of 

 the adductor impression ; p, Pallial line. 



