PLATE 33. 



Maccoya burlingtonensis (Meek and Worthen). Page 312. 



Figs. 1-5. Upper Burlington Limestone, Lower Carboniferous, Burlington, Iowa. 



Fig. 1. Same specimen as photograph, Plate 32, fig. 1. X 2.6. Ventral view. Ambulacral plates ventrally are all pri- 

 maries, with pore-pairs uniserial; at the mid-zone ambulacral plates arc alternately primaries and nearly or quite 

 occluded, with pore-pairs biserial (p. 55). Interambulacrum with two plates in the basicoronal row, three plates 

 in the second row, and four plates in the third row. (Compare text-figs. 16, p. 59; 237, p. 231.) 



Fig. 2. Same specimen as photograph, Plate 32, fig. 2. X 2.7. Ambulacral plates at the mid-zone, alternating primuiir.-s 

 and occluded, with pore-pairs biserial; at the dorsal portion representing the placogenous zone, ambulacral plates 

 are all primaries and pore-pairs are uniserial as in the youthful plates ventrally (fig. 1). Four columns of inter- 

 ambulacral plates in area A. (Compare text-figs. 10, p. 54; 237, p. 231.) 



Fig. 3. After Meek and Worthen, 1866, Plate 16, fig. 3a. Holotype. X 0.9. Four columns of plates in an interambulacral 

 area. 



Fig. 4. Mus. Comp. Zool. Coll., 3,049. External view. X 3.5. Ambulacral plates are alternately primaries and oc- 

 cluded, with pore-pairs biserial. 



Fig. 5. The same individual plates as fig. 4. Internal view. X 3.5. All ambulacral plates are primaries and pore-pairs 

 are uniserial, also the adambulacral plate is rounded on the adradial suture which it is not on the exterior (p. 60). 

 (Compare figs. 4 and 5 with Plate 34, figs. 2, 3.) 



Maccoya intermedia (Keeping). Page 314. 



Fig. 6. Lower Carboniferous, Hook Head, County Wexford, Ireland. Palaeontological Museum, Munich. X 1.8. Dor- 

 sal portion of a test. Ambulacral plates are alternately primaries and occluded, with pore-pairs biserial. Four 

 columns of interambulacral plates in area A, numerous secondary tubercles. 



Fig. 7. Same specimen. X 3.6. Ambulacral detail and tubercles. 



Fig. 8. Same specimen. X 3.5. Viewed from the interior. In this view, ambulacral plates all cross the half-areas, pore- 

 pairs are uniserial, and are farther from the interambulacral suture than on the exterior. (Compare Plate 34, figs 

 2, 3.) 



Fig. 9. The same specimen and view as fig. 8. X 6. Ambulacral plates more enlarged. 



Fig. 10. Carboniferous, Hook Head, County Wexford, Ireland (after Keeping, 1876, Plate 3, fig. 2). Sedgwick Museum, 

 Cambridge, England. Holotype. X 1.3. For structural details of this specimen see Plate 34, figs. 2, 3. 



Fig. 11. Lower Carboniferous, Hook Head, Wexford, Ireland. Sedgwick Museum Coll., Cambridge, England, 6. En- 

 larged. Four columns of plates in each interambulacral area; ocular F is exsert, all other oculars are insert. 



Fig. 12. Same horizon and locality, Sedgwick Museum, Cambridge, England. Enlarged. Genitals are in contact shutting 

 out all the oculars from the periproct, a very unusual character in the Palaeozoic (p. 89). Three or five pores in 

 each genital plate. 



Maccoya phillipsiae (Forbes). Pw 316. 



Figs. 13, 14. Caradoc conglomerate, Silurian [?], under Worcester Beacon, England (after Forbes, 1848, Plate 29, 



figs. 1, la. Holotype. 



Fig. 13. View of the specimen which is evidently poorly preserved. X 0.9. 



Fig. 14. Enlarged and partially restored. Ambulacral plates are alternately primaries and narrow occluded plates. Five 

 (?) columns of plates in an interambulacral area. 



Figs. 1, 2, 4, 5 drawn from nature, and 11, 12 from my sketches by J. Henry Blake; figs. 3, 10, 13, 14 copied by W. M. 

 Barrows; figs. 6-9 drawn by Anton Birkmaier. 



