PLATE XXXIII. 



GOSSELETTIA RETUSA. 



Page 260. 

 Fig-. 1. The left side of a well-preserved sjiecimen, showing the general form of the shell. 



Hamilton group. Eighteen Mile creek, Erie Co., N. Y. 

 Fig. 2. The antero-cardinal view of the same. 



Mytilarca occidentalis. 



Page 203. 

 See Plate 87. 

 Fig. 3. A view of the right sUe of the original of this species. 

 Fig. 4. The anterior view of the same 



Fig. 5. A left valve. The ante-byssal portion is represented as too large. See fig. 11, plate S7. 

 Yellow sandstone. Burlington. Iowa. 



Mytilarca fibristriata. 



Page 264. 



See Plate 87. 



Fig. G. A left valve. Anothei- figure of this specimen is given on plate 87. fig. 6. to show tlie foi-ni of the 



anterioi- end and the presence of radii. 

 Fig. 7. The right side of the original specimen as seen in a sulphur cast. 

 Yellow sandstones. Burlington, Iowa. 



