PLATE VIII. 



Fig. 1. — Pterinopecten rigidus. A left valve. From the Carboniferous Lime- 

 stone, Drumkeeran, co. Fermanagh. In the Collection of the Geological Survey of 

 Ireland. (Page 61.) 



Fig. 2. — Pterinopecten rigidus. A left valve. From Millicent, Clane. In the 

 Collection of the Woochvardian Museum (No. 146), Cambridge. (Page 60.) 



Fig. 3. — Pterinopecten rigidus. The shell figured by Portlock as Ortltis 

 umbraculum. A left valve. From co. Fermanagh. In the Museum of the Geo- 

 logical Survey, Jermyn Street. (Page 61.) 



Fig. 3 a. — Pterinopecten rigidus. The hinge-plate of Fig. 3. 



Fig. 4. — Pterinopecten Dumontianus. A left valve. From the Carboniferous 

 Limestone of Castleton, Derbyshire. My Collection. (Page 65.) 



Fig. 5. — Pterinopecten Dumontvmus. A left valve. From Poolvash, Isle of 

 Man. My Collection. (Page 66.) 



Fig. 5a. — Pterinopecten Dumontianus. The right valve of Fig. 5. 



Fig. 6. — Pterinopecten Dumontianus. A well-preserved left valve. From the 

 Carboniferous Limestone of Craven. In the York Museum. (Page 65.) 



Fig. 7.- — Pterinopecten Dumontianus. A left valve, showing rather coarser ribs. 

 From the Carboniferous Limestone of Castleton. My Collection. (Page 65.) 



Fig. 8. — Pterinopecten Dumontianus. A full-grown left valve. From the 

 Carboniferous Limestone of Settle. In the Collection of the Woodwardian Museum 

 (No. 152). (Page 66.) 



