185 



Big Sturgeon Island, Lake Winnipeg, D. B. Bowling and L. M. Lambe, 

 1890 : a cast of the interior of both valves, from a loose piece of limestone. 



Ctenodonta subnasuta, Ulrich. 



Ctenodonta suhnasuta, Ulrich 1894. Lower Silur. Lamellibr. Minn., p. 585, 



pi. 42, figs. 34-,S6. 



Cat Head, Lake Winnipeg, D. B. Bowling, 1891 : a well-preserved 

 cast of the interior of a left valve. Considering the section of the genus 

 to which this species belongs, the strength and definition of the muscular 

 scars, pallial line, and hinge denticles, and in fact the whole characters 

 of the cast, would seem to shew that it was made by an adult shell and 

 not by a young specimen of Ctenodonta (or Tellinomya) ovata, Hall. In 

 the Cat Head specimen the denticles bend toward and not away from the 

 beak. 



ClINOPISTHA (?) ANTIQUA. (N. Sp.) 

 Plate 20, fig. 6. 



Shell equivalve, compressed convex but lightly inflected above and 

 behind the subangular posterior umbonal slopes, elongate, about twice as 

 long as high, and rather narrowly subelliptical. Anterior side longer and 

 broader in the direction of its height than the posterior, its extremity 

 somewhat narrowly rounded, posterior side short and truncate or sub 

 truncate at the end : umbones depressed, beaks incurved, and placed a 

 little behind the midlength. 



Surface markings unknown, as the test is not preserved,! but the cast 

 of the interior of both valves is nearly smooth and marked only with a 

 few faint concentric striae of growth. 



Hinge dentition unknown, though the test appears to have been very 

 thin and the hinge practically edentulous. Immediately behind the beaks 

 there are indications of a short external ligament. Pallial line and 

 anterior muscular impression unknown, but the posterior muscular im- 

 pression seems to have been shallow, rather large, subovate or somewhat 

 wedge-shaped in outline and longer than high. 



Length of the most perfect specimen collected, 31 mm. ; height of the 

 same, at the midlength, 15 mm. 



Inmost or Birch Island, Kinwow Bay, Lake Winnipeg, D. B. Bowling 

 and L. M. Lambe, 1890 : a perfect but not very well preserved cast of 

 the interior of a specimen with both valves widely open. An imperfect 

 natural mould of the exterior of a specimen which is probably referable 

 to this species, had previously been collected at the same locality by Mr. 

 Weston in 1884. 



