PLATE XXIV. 



Pentacekos abbreviatds, n. sp. (Page 80.) 



From the Upi)er Chalk. 



Fig. 



1. Abactinal aspect; natural size. (Coll. Brit. ]\Ius., 575:^S.) 



a. Lateral view of arm ; natural size. 



b. Radial plate ; magnified 3 diameters. 



c. Two succeeding supero-marginal plates; magnified :] diameters 



Pentaceros C0R0NATU8, Forbcs, sp. (Page 82.) 

 From the Lower Chidl-. 



2. Abactinal aspect ; natural size. (Coll. Brit. ]\Ius., o5480.) 



a. Plate of disc ; magnified 3 diameters. 



b. Supero-marginal plate ; magnified 3 diameters. 



c. Lateral view of arm ; natural size. 

 [See also PL XXV, fig. 9.] 



