PLATE 10. 



Archaeocidaris longispina Newberry. Page 261. 



Fig. 1. Carboniferous (Coal Measures), North Arizona. Columbia Univ. Coll., 6,419 G, holotype. Natural si/.c. 

 Spines smooth, straight, inflated. 



Archaeocidaris glabrispina (Phillips). Page 261. 



Fig. 2. Lower Carboniferous, Hook Head, Ireland. Sedgwick Museum, Cambridge, England, a, spine X 1.9; b, base of 

 spine more enlarged. The spine is smooth, straight, inflated. 



Archaeocidaris legrandensis Miller and Gurley. Page 200. 



Fig. 3. Kinderhook Group, Lower Carboniferous. Le Grand, Iowa. Univ. of Chicago Mus. Coll., 12,314. X 8.7. 



Four columns of plates in an interambulacral area, scrobicular ring well developed. 

 Fig. 4. Same horizon and locality. Univ. of Chicago Coll., 6,198, holotype. X 1.8. Interambulacral plates with smooth 



primary spines in place. 



Archaeocidaris nerei (Munster). Page 262. 



Fig. 5. Lower Carboniferous, cotypes, enlarged. X about 2. (After Munster, 1839, Plate 3, figs. 6a-6d.) a, an adni- 

 dial interambulacral plate; b, spine; c, possibly a brace of the lantern; d, a left half-pyramid. 



Figs. 6, 7. After Muller, 1857, Plate 3, figs. 12, a, b. X 2.7. 



Fig. 6. Pyramid, face view, moderately deep foramen magnum (p. 363). 



Fig. 7. Pyramid in side view with ridges for the attachment of interpyramidal muscles. 



Archaeocidaris glabrispina (Phillips). Pago 2U. 



Fig. 8. Lower Carboniferous, Limestone, Ireland (after Baily, 1877, p. 18, figs. a-e). Cotypes of Archaeocidaris stetti- 

 fera Baily, here considered a synonym. Details of plate ornamentation in figs, a-c are very doubtful; d, spine, smooth, 

 swollen; e, base of same enlarged. 



Fig. 9. Lower Carboniferous, Miatschkowa, near Moscow, Russia (after Trautschold, 1879, Plate 2, fig. without a number). 

 The holotype of Archaeocidaris laeris Trautschold, here considered a synonym. Spine smooth, inflated. 



Archaeocidaris rossica (Buch). Page 263. 



Fig. 10. Lower Carboniferous, Miatschkowa, Province of Moscow, Russia. Palaeontological Museum, Munich. X 1.8. 

 Same specimen as Plate 11, figs. 1, 2, spread out on the Lov6n method. Ambulacra conform to the outline of the 

 interambulacra, four columns of plates in each interambulacrum. Interambulacral plates are high hexagonal, 

 elongating dorsally. Basal terrace developed, but wanting in the younger plates dorsally; primary tubercles im- 

 perforate in younger plates dorsally, and in the youngest plates there is no tubercle developed. In areas A, G, and I, 

 the plates of the basicoronal row from left to right (of the area) are in the sequence of a large plate, small plate; large 

 plate, small plate. Therefore column 4 lies to the right of the center. In areas C and E, on the contrary, the sequence 

 from left to right is a small plate, then a large one; another small plate and a large one. In this arrangement column 4 

 lies to the left of the center. This relation of the sequence of large and small plates in the basicoronal row, and its 

 relation to the position of column 4 will be understood by the schematic figure, Plate 9, fig. 8, where the plates remove 1 

 by resorption are restored in accordance with the rules observed in other Palaeozoic Echini. Strongly imbricating 

 scale-like ambulacra! and non-ambulacral plates occur on the peristome. (See text-fig. 239 bis. p. 264.) 



Archaeocidaris sixi Barrois. Page 447. 



Fig. 11. Carboniferous, Assize de Lena, Ontoria, Sebarga, Spain. Cotypes (after Barrois, 1882, Plate 16, figs. 5a-5c). 

 a, b. interambulacral plate in face and side views. X 0.9. c, spine, flattened, vertically striate, the form of the cross 

 section is shown above. X 2.8. On account of the small size and flattening, this is apparently a secondary, not a 

 primary spine. 



Archaeocidaris pizzulana Gortani. Page 273. 



Fig. 12. Carboniferous, Forca Pizzul, Carnic Alps, Italy, cotypes (after Gortani, 1905, Plate 15, figs. 29, 30, 31, 33). a, b, 

 interambulacral plates: c, primary spine with thorn-like spinules set opposite one another. X 0.9. d, base of spine 

 showing annulus. 



Figs. 5 and 9 drawn by W. M. Barrows; all others by J. Henry Blake. 



