Fitrure 1- 



la. 



Figure 2. 



20. 

 2h. 



Fisj-ure 



3a. 

 35. 



Figure 



Figure 



Figure 



4. 

 4a. 



5. 

 5a. 



6. 

 6a. 



Figure 7. 



7a. 



Figure 8. 



«a. 



ah. 



PLATE in. 



AcROLoxus RADiATULUs (page IT). 



Tlie type specimen, fromtlie mouth of the Blind Man River, as 

 seen from above and shghtly enlarged. The cross-lines to 

 the right indicate the actual size. 



A portion of the surface of the same, stiil more highly magni- 

 ffed, to shew the details of the sculpture. 



Anchistoma parvulum (page 19). 



View of the upper side of the only specimen known. 



Basal view of the same. 



Another view of the same, to show the proportionate height or 



convexitj' of the shell, and the narrow lobe on the upiwr 



pai't of the outer lip. 



Thaujiastus limn^eiformis (pages 2(i and 27). 



Dorsal view of a specimen of a supposed varietjf of this species, 



from the Rosebud River. 

 Outline of another and apparently more typical spjeeimen, from 



Wood End Depot. 

 Ventral view of the lust, to shew the characters of the aperture. 



GoNioBAsis Nebra.scensis (page 21). 



Dorsal view of a specimen fromtlie St. ]\Iary River. 

 Portion of the same magnified, to shew the surface markings. 



GoNiOBASis tendicarinata (page 22). 



Dorsal view of a si:iecimen from the Bow River. 

 Enlarged portion of tlie same, to shew the sculpture of the last 

 volution of the spire. 



GoNiOBASis TEN'iricARiNATA, Var., (page 22). 



Specimen from Pincher Creek, dorsal ^•iew. 



Similar view of another and slightly distorte<l example from 

 the same locality. 



Valvata kilos a (page 25). 



Magnitied representation of a perfect specimen from Pincher 

 Creek, showing the upper surface. The cross-lines on the 

 right indicate the actual size. 



Portion of the surface of the same, still more highly magnitied, 

 to shew the sculpture. 



Valvata bicincta (page 25). 



Specimen from the mouth of the Blind JIan River, as seen from 

 above, and considerably enlarged. The cross-lines between 

 this and the next figure shew the actual size of the originals 

 of Ijoth. 



Basal view of the same, also enlarged- 



A portion of the surface of the same specimen, still more highly 

 magnified, to shew the details of the surface markings. 



