PLATE XVIII. 



ACTINOPTERIA DECUSSATA. 



■ ill 

 See Plates 17. 20 and 84. 

 Fig, i . '. n ing the lamellse of the test. 



Encrinal li stone of the Hamilton group. Eighteen Milt crt k, N. Y. 



Pig. •_'. The right valve of a specimen preserving both valves. The left valve is n 



Hamilton group. York, Livingston Co., N. Y. 

 Pig. 3. \ right valve. The specimen preserves several rays on the wing which are not i ■ I ii; 



the figure. 



Hamilton group. Qeneseo, /.• b., .V. Y. 



I. A -mall righl valve showing the radii on the wing. 

 Hamilton group. Ontario Co., N. Y. 

 Fig. 5. A small left \ alve. 



Hamilton group. Canandaigua lake, N. Y. 

 Pig. i;. The lefl valve of the specimen, fig. i. 

 Pig. 7. A left \ alve preserving a portion of the test on the anterior end. 



Hamilton group. Livingston Co., N. Y. 

 Fig. s. A cast of a left valve. 



Encrinal limestone of the Hamilton group. Eighteen Mill creek, X. Y. 

 Fig. 9. The left valve of the specimen fig. -■ 

 Fig. 10. \ left valve showing very fine surface radii. 



Hamilton group. York, Livingston Co., X. 1'. 

 II. A similar specimen of more elongate form. 



Hamilton group. Bellona, Yates Co., JV. 1". 

 Fig. 12. A large left valve preserving the greater portion of the test. 



Encrinal limestone of the Hamilton group. Eighteen Mil' creek, Erii Co., iV. Y. 

 Fig. 13. A lefl valve enlarged to two diameters showing the characters of surface in a well-preserved 



specimen. 

 Fig. i i. A farther enlargement of the surface, to show the elevated lamella- ami the mode of increase of the 



radii. 

 Fig. 15. Cardinal view of a Bpecimen preserving both valves partly opened. 

 Hamilton group. York, Livingston '". .V. V. 



