PLATE XXI. 



Pentaceeos bulbiferus, Forbes, sp. (Page 77.) 



From the Upper Chalk. 

 Fig. 



1. View of the extremities of three arms and portion of disc; natural size. 

 (Coll. Brit. Mus., E. 5040.) 



a. Ventro-lateral plate; magnified 6 diameters. 



b. Actinal view of the extremities of two of the above arms ; natural size. 



Pentagonaster robustus, n. sp. (Page 73.) 

 From the Upper Chalk. 



2. Abactinal aspect; natural size. (Coll. Brit. Mus., 48085.) 

 a. Lateral view of an arm ; natural size. 



Pentaceros bulbiferus, Forbes, sp. (Page 77.) 

 From the Upper Chalk. 



3. Abactinal aspect; natural size. (Coll. Brit. Mus., E. 5041.) 

 a. Madreporite ; magnified b' diameters. 



4. Abactinal aspect ; natural size. (Coll. Brit. Mus., 40399.) 

 a. Madreporite ; magnified 6 diameters. 



