ARCHAEOCIDARIS. 263 



attachment of interpyramidal muscles (p. 363). Miiller's figures of interambulacral plates are 

 rather doubtfully referable to this species, but, as I show in A. rossica, plates differ enough in 

 different parts of the test so that we must allow considerable latitude. Julien's figures are not 

 recognizable, but his description appears to make his specimen referable to this species. 



Lower Carboniferous, Regnitzlosau ; Tournay, Belgium; Miinster's cotypes of both nerei 

 and protei are in the Munich Museum; Tournay, Belgium, British Museum Collection 32,847; 

 Museum of Comparative Zoology Collection; La Varville and Sigaret (Julien) ; Assise de Lena; 

 Villaneueva, Spain (Barrois). The references given to American localities by Desor and other 

 European authorities are probably incorrect. 



*Archaeocidari3 rossica (Buch). 

 Text-figs. 208, p. 1S4; 239 bi^, p. 264; Plate 10, fig. 10; Plate 11, figs. 1-5; Plate 12, figs. l-13k. 



(?) Cidaris dcuailionis Eiehwald, 1S41, p. SS. [Description is unrecognizable so the name cannot hold.] 



Cidaris rossicus Buch, 1842, p. 323. 



Cidarites rossicus Murchison, Verneuil and Keyserling, 1845, p. 17, Phite 1, figs. 2a-2e. 



Palaeocidaris rossica L. Agassiz and Desor, 1846-'47, p. 367. 



Echinocrinus rossica d'Orbigny, 1850, p. 154. 



Palaeocidaris {Echinocrinus) rossica Vogt, 1854, p. 314. 



Eocidaris rossica Desor, 1858, p. 156, Plate 21, figs. 3-6. 



Echinocrinus dcucalionis Eiehwald, 1860, p. 652. 



Eocidaris rossicus Geinitz, 1866, p. 61. 



Archacocidaris rossicus Trautschold, 1868, Plate 9, figs. 1-lOb; 1879, p. 6, Plate 2, figs, la-lf, Ih, li, 



Ik, 11; Quenstedt, 1875, p. 373, Plate 75, fig. 12; Klem, 1904, p. 55. 

 Archaeocidaris rossica Loven, 1874, p. 43; Tornquist, 1896, text-fig. p. 27, Plate 4, figs. 1-5, 7, 8. 

 Archacocidaris rossica var. schcllwieni Tornquist, 1897, p. 781, Plate 22, fig. 12. 

 Cidarolropus rossica Lambert and Thiery, 1910, p. 125. 



This species is known from the most nearly complete material of any species of the genus ; 

 coming from the soft yellow calcareous clay beds of Moscow, the material is not distorted and 

 is easily cleaned. Test compressed, spheroidal, about the form of a living cidarid. Ambulacral 

 areas are narrow, sinuous, conforming to the outline of the adambulacral plates (Plate 10, fig. 

 10). Ambulacral plates are low, imbricating moderately ventrally and strongly beveled under 

 the adambulacrals (Plate 12, fig. 9). Pore-pairs are uniserial. There are four columns of 

 plates in each interambulacral area. The plates at the mid-zone are higher than wide ; ventrally 

 they are not relatively so high, but dorsally are much higher than at the mid-zone; near the 

 apical disc the young plates are very small, and smooth. The primary tubercles are strongly 

 marked, scrobicular area large, basal terrace well developed at the mid-zone (Plate 11, fig. 4), 

 and ventrally, but dorsally in the younger plates no terrace is developed. Passing dorsally to 

 the still younger plates, it is seen (Plate 11, fig. 2) that the scrobicule is imperfectly developed, 



