26G CATALOGUE OF THE BLASTOIDEA. 



Doubtful Sjjccies. 

 Codaster Americanus, Shumard. Upper Helderberg Group, Lower Devonian ; 



Kentucky. 

 Codaster pulchellus, Miller & Dyer. Niagara Group, Upper Silurian ; Indiana. 

 Pentremites subtruncatus, Hall. Hamilton Group, Upper Devonian; Iowa. 

 Codaster Whitei, Hall. Burlington Limestone, Subcarboniferous ; Iowa. 



Distribution. If Codaster pulchellus, Miller & Dyer, from the Niagara Group of 

 Indiana be rightly so named, this genus has the most extended geological range of 

 all the Blastoidea. Commencing in the Upper Silurian of America, it is well 

 represented both in the Upper Helderberg and in the Hamilton Group of the 

 Devonian Period, especially the latter; while the doubtful C. Whitei, Hall, occurs 

 in the transition-bed between the Upper Burlington and the Keokuk Limestones 

 of the American Subcarboniferous. The type species (C. trilobatus) is fairly abundant 

 in the Carboniferous Limestone of Lancashire and Yorkshire, and may be considered, 

 we suppose, as the last survivor of the genus. 



Type. Codaster trilobatus, McCoy. 



1. SPECIES FROM THE DEVONIAN. 

 a. Obpyriform Species. 



Codaster pyramidatus, B. F. Shumard. 



(PI. XII. figs. 1-3.) 



('ml uster (dternatus, Lyon {fide Wachsmuth ') , Owen's 3rd Report Geol. Survey Kentucky, 



1857, p. 493, t. 5. f. 3, b (excl. f. 3, a). 

 Codaster pyramidatus, Shumard, Trans. St. Louis Acad. Sci. 1858, vol. i. no. 2, pp. 238 & 247, 



t. 9. f. 1, a-e, ibid. 1865, vol. ii. no. 2, p. 359. 

 Codaster pyramidatus, Hall, Fifteenth Ann. Report New York State Cab. Nat. Hist. 18G2, 

 p. 152, t. 1. f. 12 & 13. 



Sp. Char. Calyx obpyramidal, tapering rapidly to the small attenuated base; 

 summit moderately convex; section distinctly pentagonal; periphery at the distal 

 ends of the ambulacra, near the summit. Basal plates forming a small, almost 

 round, attenuated cup, less than one third the height of the calyx, terminating 

 below in a triangular surface, slightly concave. Radial plates elongate, longer than 

 wide, gradually expanding in width upwards; bodies almost double the length of 

 the limbs, each marked by a rounded triangular ridge which narrows gradually 

 upwards till it reaches the inconspicuous lip; interradial sutures placed in depres- 

 sions ; sinuses triangular, short, and wide, with inwardly bevelled or sloping sides ; 



1 Report Geol. Survey Illinois, 1883, vol. vii. p. 354 (note). 



