PLATE XXXIII. 



GOSSELETTIA RETUSA. 

 Page 266. 

 Fig. I. The left side of a well-preserved specimen, 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 occidentals. 



Page '263. 

 See Plate 87. 

 Fig. 3. A view of the right sitle 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 87. 

 Yellow sandstone. Burlington, Iowa. 



Mytilarca fibristriata. 



Page 2B4. 



See Plate 87. 



Fig. G. A left valve. Another figure of this specimen is given on plate 87, fig. 6, to show the form of the 



anterior 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. 



