PLATE 16. 

 Lepidocidaris squamosa Meek and Worthen. Page 282. 



Fig. 1. Lower Burlington Limestone, Lower Carboniferous, Burlington, Iowa. Mus. Comp. Zool. Coll., 3,026. Holo- 



type. Natural size. Every third arabulacral plate is higher than the intermediate plates; eight columns of inter- 



ambulacral plates in area A. Drawings, Plate 17, figs. 1-5. 

 Fig. 2. Same horizon and locality, F. Springer Coll., 8,096. Natural size. Six columns of interambulacral plates in 



area A, primary spines in place. Drawings, Plate 17, figs. 7, 8, 10, 12, 14. 

 Fig. 3. Same horizon and locality, F. Springer Coll., 8,098. Natural size. Very clear for the surface characters of 



interambulacral plates. 



Echinocystites pomum Wyville Thomson. Page 252. 



Fig. 4. Lower Ludlow, Silurian, Leintwardine, England, Museum of Practical Geology Coll., London, 7,385. (Original 

 specimen of Sir Wyville Thomson's, 1861, Plate 3, fig. 3.) Cotype. Natural size. A ventral view, the outline 

 of the ambulacra] and interambulacral areas clearly defined. Tubercles and spines are visible on the interambulacra 

 and an excellent lantern is in place. 



Lepidocentrus drydenensis (Vanuxem). Page 288. 



Fig. 5. Chemung Group, Upper Devonian, Dryden, New York. New York State Museum Coll., 4,200. Holotype. 

 Natural size. The specimen is an internal mold of the ventral side, combined with some external features as spines. 

 Drawings, Plate 21, figs. 1-3. On the same slab are additional incomplete impressions of other specimens of this 

 species; these, with that figured, are the only known specimens of the species. 



Fig. 1 from photograph by H. W. Tupper; figs. 2, 3, 5 by F. A. Saunderson; fig. 4 by J. W. Tutcher in London. 



