PLATE XVIII. 



Artheaster Dixoni, Forht'ft. (Page 91.) 



From the Lower CJialk. 

 Fig. 



1. Actinal aspect ; natural size. (Coll. Brit. Mus., 47000.) 

 a. Supero-marginal plate ; magnified 3 diameters. 



CoMPTONiA CoMPTONij Fovhc's, sp. (Page 69.) 



From the Upper Greensand. 



2. Abactinal view ; natural size. (Coll. Nortliampton Mus.) 

 a. Isolated plate of interradial portion of disc ; magnified 6 diameters. 

 h. Isolated radial ; magnified G diameters. 



c. Lateral view of interbrachial arc ; natural size. 



d. Supero-marginal plate ; magnified 3 diameters. 



