298 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



species of Chonetes and fragments of a large fish. There 

 is also here a large Stromatopora, probably S. concentrica. 



At Thunder Island, St. Martin Lake, the Stromatopora 

 occurs, with abundance of a small Strophomena and some 

 corals, not determinable. 



Lucina Occidentalis. (N. S.) 



Oval, length about one-ninth greater than the width, 

 hinge line greatly convex, cardinal extremities obtusely 

 rounded, aDterior and posterior margins gently convex, 

 sub-parallel ventral margin rounded or a little pointed in 

 the centre ; beaks central, small, pointed, incurved, nearly 

 in contact with each other, and turned a little towards the 

 anterior extremity ; both valves moderately convex and 

 marked with concentric undulations of growth. 



Length of specimen, nine lines, width eight lines, depth 

 of both valves, five lines. The greatest width is at about 

 one-fourth the length below the beaks, from which level 

 the margins converge but little, until within two-fifths of 

 the length of the front, when they become more strongly 

 curved. 



Locality and Formation, Snake Island, Lake Winnipego- 

 sis. Devonian.] 



