168 



Obolus Galtensis. (N. sp.) 



Fig. 151. Fig. 152. 



Fig. 152. — Obolus Galtensis. 



Description. — Ovate, both valves moderately convex ; sides gently, and 

 front margin broadly rounded ; apical extremity of ventral valve 70° ; 

 greatest width a little below the middle. The area of the ventral valve is 

 flat, with a concave groove along the middle ; and while in one specimen 

 it lies nearly in the plane of the margin, in another it slopes a little 

 outwards. 



The largest specimen seen is 25 lines in length and 18 in width. 



Locality and Formation. — Gait. In the Guelph formation; Middle 

 Silurian. 



Collectors. — E. Billings, R. Bell. 



Orthoceras Piso. (N. sp.) 



Description. — Section circular, taperuig eight lines in a length of five 

 inches ; septa moderately concave, about twelve to the inch ; siphuncle 

 moniliform, dilated, between the septa, to a diameter of about 1^ Imes, its 

 centre distant about three lines from the margin, where the diameter of 

 the fossil is 10 lines. The shell is preserved on the specimen, and appears 

 to be quite smooth, but this may have been caused by cleaning it from the 

 adhesive shale in which it was found imbedded. It is most probably 

 marked with fine engirdling striae. 



The specimen is 5 inches in length ; width at the larger extremity 14 

 lines, and at the smaller 6 lines. 



Locality and Formation. — Cape Smyth, Lake Huron. In the Hudson 

 River group. 



Collector.— K. Bell. 



