PLATE XVIII. 
Actinopteria decussata. 
Page 111. 
See Plates 17, 20 and 84. 
Pig. 1. A large right valve, preserving the lamellae of the test. 
Encrinal limestone of the Hamilton group. Eighteen Mile creek, N. Y. 
Fig. 2. The right valve of a specimen preserving- both valves. The left valve is represented in fig. 9. 
Hamilton group. York, Livingston Co., N. Y. 
Pig. 3. A right valve. The specimen preserves several rays on the wing which are not represented in 
the figure. 
Hamilton group. Geneseo, Livingston Co., N. Y. 
Pig 4. A small right valve showing the radii on the wing. 
Hamilton group. Ontario Co., N. Y. 
Fig-. 5. A small left valve. 
Hamilton group. Canandaigua lake, N. Y. 
Fig. ' 6. The left valve of the specimen, fig. 4. 
Pig. 7. A left valve preserving a portion of the test on the anterior end. 
Hamilton group. Livingston Co., IS. Y. 
Fig. 8. A cast of a left valve. 
Encrinal limestone of the Hamilton group. Eighteen Mile creek, N. Y. 
Pig. 9. The left valve of the specimen fig. 2. 
Fig-. 10. A left valve showing very fine surface radii. 
Hamilton group. York, Livingston Co., N. Y. 
Fig. 11. A similar specimen of more elongate form. 
Hamilton,group. Bellona, Yates Co., N. Y. 
Fig. 12. A large left valve preserving the greater portion of the test. 
Encrinal limestone of the Hamilton group. Eighteen Mile creek, Erie Co., N. Y. 
Fig. 13. A left valve enlarged to two diameters showing the characters of surface in a well-preserved 
specimen. 
Fig. 14. A farther enlargement of the surface, to show the elevated lamellae and the mode of increase of the 
radii. 
Fig. 15. Cardinal view of a specimen preserving- both valves partly opened. 
Hamilton group. York, Livingston Co., N. Y. 
