PLATE XXIX. 



Page 



Figs. 1-6. Thoracaster cylindratus, n. sp. . . . 168 



Fig. 1. Abactinal aspect; natural size. 



Fig. 2. Actinal aspect ; natural size. 



Fig. 3. Profile view ; natural size. 



Fig. 4. A portion of the abactinal surface ; magnified 10 diameters. 



Fig. 5. Mouth-plates ; magnified. 



Fig. 6. A portion of the actinal surface of a ray, showing adambulacral plates 

 and infero-marginal plates ; magnified 10 diameters. 



