243 Mr. T. R. Jones on North American 



noticed by the geologists of the United States ; and some of 

 these I bchcve I have satisfactorily recognized in specimens at 

 my command ; about some of the others I am still in much 

 doubt ; and some I have not as yet seen. 



I proceed to describe the species : first, those from Beechey 

 Island ; 2ndly, those from Canada ; 3rdly, those from the United 

 States. 



{From Beechey Island.) 



1. Beyrichia rugulifera, spec. nov. PI. IX. fig. 4. 



Length -j^, breadth ^^ inch. 



A " simple" or unisulcate Beyrichia ; nearly oblong, narrow ; 

 extremities nearly equal ; ventral margin faintly convex ; dorsal 

 notch broad and deep. Surface of valves ornamented with a 

 delicate sculpturing of irregular, interrupted, somewhat sinuous, 

 tapering, little grooves, arranged vertically (transverse to the 

 long axis of the valve), appearing like a system of minute 

 wrinkles. 



From Beechey Island, in the limestone containing Leperditia 

 gibbera. (See Annals Nat. Hist.* 2nd ser. vol, xvii. p. 91.) 



2. Berjrichia sigillata, spec. nov. PI. IX. fig. 5. 



Length ^j^, breadth -^^ inch. 



Unisulcate, ovato- oblong, ends and belly well rounded, and 

 margined by a broad, uniform, depressed rim ; dorsal notch 

 distinct^ narrow. Surface of valves marked with numerous 

 distinct, irregularly oval pits. 



Beechey Island, with the foregoing. 



3. Beyrichia clathrata, spec. nov. PI. IX. fig. 1. 



Length J^, breadth ^'^ inch. 



A bisulcate form ; the surface of the valve presenting a large 

 horseshoe-shaped lobe, and a small, rounded, subcentral lobe ; 

 the latter being limited and almost surrounded by the two dorsal 

 notches. Anterior portion of the valve somewhat puckered ver- 

 tically, — a feature which is carried to an extreme in the next 

 species, B. plagosa. Surface of the valves ornamented by a 

 bold pattern of broad, shallow, subangular pits, having a some- 

 what radiate arrangement as regards the centre of the valve. 



From Beechey Island, with the foregoing. 



* 1 omitted to mention that the right valve figured in PI. 7- fig- 8, 

 was brought from Beechey Island by Dr. Armstrong, among other fossils. 



