I'l.ATK 1-1 (continued). 

 Archaeocidaris megastyla Shumard and Swallow. Page 273. 



Fig. 13. Si. Ixmi.s Group, Lower Carboniferous, St. Louis. Missouri. II. S. Nat. Mus. Coll., 43,009. X 0.9. Interam- 

 bulacral plates with primary and secondary spines in place, the primary having strong, thorn-like, widely .spaced 

 spinules. 



Archaeocidaris triserialis (M'Coy). Page 275. 



Fig. 14. Arenaceous Limestone, Lower Carboniferous, Killycloghy, Lisbellow, County Tyrone, Ireland (after M'Coy, 

 1844, Plate 26, fig. 1). Griffith Collection, Science and Arts Mus. Coll., Dublin. Holotype. X 0.9. Spines with 

 three series of serrate spinules directed distally. Same specimen as photograph, Plate 8, fig. 10. 



Archaeocidaris triserrata Meek. Page 275. 



Fig. 15. Upper Carboniferous, near Omaha, Nebraska (after Meek, 1872, Plate 1, figs. 6a-6c). U. S. Nat. Mus. Coll. 

 6,599. Cotypes. a, base of spine, X about 4; b, c, spines with serrate spinules, enlarged a little less than X 2. 



Archaeocidaris urii (Fleming). Page 270. 



Fig. 16. Lower Carboniferous, Ireland (after Portlock, 1843, Plate 16, fig. 11, who figured it as Cidaris vetusla). Inter- 

 ambulacral plate. Natural size. (Probably the specimen in the Jermyn Street Museum, 7,768, see p. 278.) 



Archaeocidaris wervekei Tornquist. Page 276. 



Fig. 17. Lower Carboniferous, Hunsriicken, Germany (after Tornquist, 1897, Plate 22, figs. 2a, 2b, 3, 9, 10). Cotypes. 

 a, hexagonal interambulacral plate, natural size; b, the same, enlarged, basal terrace pronounced; c, an adradial 

 plate enlarged; d, a plate in profile; e, f, spine natural size, and detail enlarged, with nodose spinules, arrange-! in 

 vertical series. 



Archaeocidaris urii (Fleming). Page 276. 



Fig. 18. Lower Carboniferous, Ireland (after M'Coy, 1844, Plate 27, fig. 1). 



Fig. 19. Lower Carboniferous, Hayfod-y-Calch, Corwen, Wales; Sedgwick Museum, Cambridge (after Keeping, 1S7G, 



Plate 3, figs. 14, 15, 18). X 0.9. a, dissociated plates as they occur on the slab; b, an adradial plate, basal terrace 



clearly defined; c, a peculiar plate of unknown nature from fig. a, enlarged (p. 278). 

 Fig 20. Lower Carboniferous, Benburb, County Tyrone, Ireland (for the locality of this specimen see discussion, p. 278), 



(after Portlock, 1843, Plate 16, figs. lOa-lOd, where it is called Cidaris benburbensis Portlock, of which species it 



is the holotypeX Museum of Practical Geology Coll., London, 7,659. a, spine, natural size and enlarged; b, c, 



plates, natural size. 



Figs. 9 and 13 drawn by J. Henry Blake; all others copied by W. M. Barrows. 



