PLATE XXII. 



PENTAGONASTER OBTUSUS, Forbes, sp. (Page 74.) 



From the Upper Chalk. 



FIG. 



1. Abactinal aspect ; natural size. (Coll. Brit. Mus., 40400.) 



a. Madreporite ; magnified 10 diameters. 



b. Lateral view of margin, abactinal side upwards ; natural size. 



2. Actinal aspect of two specimens; natural size. (Coll. Brit. Mus., 35481.) 



a. Lateral view of extremity of arm of the underlying specimen ; natural size. 

 3 a. Dorsal view of extremity of arm ; natural size. (Coll. Brit. Mus., E. 5039.) 



b. End view of extremity of arm ; natural size. (Coll. Brit. Mus., E. 5038.) 



c. Side vieAV of extremity of same arm ; natural size. 



d. Ventral end of extremity of same arm ; natural size. 



e. Supero-marginal plate ; magnified 3 diameters. 

 /. Infero-marginal plate ; magnified 3 diameters. 

 g. Adambulacral plate ; magnified 5 diameters. 



PENTACEROS BOYSII, Forbes, sp. (Page 80.) 

 From the Upper Chalk. 



4. Abactinal view ; natural size. (Coll. Brit. Mus., 46600.) 



a. Isolated ossicle of disc ; magnified 4 diameters. 



b. Isolated ossicle of disc ; magnified 4 diameters. 



c. Lateral view of arm ; natural size. 



