PLATE XXIV. 



PENTACEROS ABBREVIATOS, n. sp. (Page 86.) 



From the Upper Chalk. 



FIG. 



1. Abactinal aspect; natural size. (Coll. Brit. Mus., 57538.) 



a. Lateral view of arm ; natural size. 



b. Radial plate ; magnified 3 diameters. 



c. Two succeeding supero-marginal plates ; magnified 3 diameters. 



PENTACEROS COROXATUS, Forbes, sp. (Page 82.) 

 From the Lower Chalk. 



2. Abactinal aspect ; natural size. (Coll. Brit. Mus., 35480.) 



a. Plate of disc ; magnified 3 diameters. 



b. Supero-marginal plate ; magnified 3 diameters. 



c. Lateral view of arm ; natural size. 

 [See also PI. XXV, fig. 9.] 



