100 CANADIAN FOSSILS. 



Two separate valves of this curious and rather obscure form (so 

 much resembling Bairdia siliqua of the Chalk, and the recent B. Minna) 

 occurred in the limestone from Pauquette's Rapids. 



TX. Cytheropsis rugosa, Jones. 



{Annals of Natural History, 3d series, vol. i. p. 249, plate x. fig. 5.) 



Length g^, breadth ^\ inch. 



Small, convex, subreniform, broad, rounded at both ends, the an- 

 terior one of which is smaller than the other. Coarsely sculptured with 

 broad shallow pits. One specimen, showing the two valves united, 

 and of a light-brown color, occurred with the many other Entoraos- 

 traca in the small specunen of limestone from Pauquette's Rapids. 



Locality and Formation. — Pauquette's Rapids. 



Collector. — Sir W. E. Logan. 



To give a general view of the distribution of the known species 

 and varieties of Bivalved Entomostraca in the Lower Palaeozoic strata 

 of the United States, Canada, and Arctic America, the following 

 Table is appended : — 



