272 ROBERT TRACY JACKSON ON ECHINI. 



*Archaeocidaris cratis White. 

 Plate 14, fig. 6. 



Archacocidaris cratis White, 1876, p. 109; 1880, p. 130, Plate 33, fig. 2a; Keyes, 1895, p. 188; Girty, 



1903, p. 331; 1908, p. 110; Klem, 1904, p. 47; Lambert and Thiery, 1910, p. 125. 

 Archacocidaris sp. a, Girty, 1908, p. 110. 



Known only from primary spines, which are slender, tapering, terete, shaft with sharp, 

 distinct, distant spinules, each about 1.5 mm. long and pointing distally. Length of spine 

 about 60 mm., diameter just above milled ring about 4 mm. Differs from mucronata in that 

 the spine is more slender, terete, and spinules more widely and irregularly distributed. 



Girty's (1908) species "a" may well be considered an immature spine of an adult, or the 

 spine of a young individual of cratis. 



Carboniferous (Coal Measures) at confluence of the Grand and Green Rivers, Utah, holo- 

 type from this locality in United States National Museum Collection 8,235 ; Nebraska. Crested 

 Butte district; Leadville district and Ouray, Colorado (Girty). Guadaloupe Point, Guada- 

 loupe Mountains, Texas (Girty). 



Archaeocidaris acanthifera Trautschold. 

 Plate 14, figs. 7, 8a, 8b. 



Archacocidaris acanthifera Trautschold, 1879, p. 7, Plate 2, fig. lu [no number on figure on the Plate]. 

 Archaeocidaris sp. Hind, 1905, p. 529, Plate 25, figs. 1, la. 



Known only from primary spines, which are slender, tapering, with long irregularly placed 

 spinules pointing moderately distally. The specimens figured by Hind appear referable to 

 this species, although the spinules are not so long as in the type. These specimens are from the 

 Coal Measures of Staffordshire, England, and are apparently the only Palaeozoic Echini yet 

 recorded in Europe from the Coal Measures. 



Lower Carboniferous, Miatschkowa, Province of Moscow, Russia (Trautschold). Coal 

 Measures, Nettlebank, Staffordshire, England. 



Archaeocidaris pizzulana Gortani. 

 Plate 10, figs. 12a-12d. 



Archaeocidaris pizzulana Gortani, 1905, p. 586, Plate 15, figs. 29-33, 36f. 

 Cidarotropus pizzulana Lambert and Thiery, 1910, p. 125. 



Known from dissociated interambulacral plates and spines. Interambulacral plates are 

 hexagonal, wider than high, with a double ring of secondary tubercles on the margin. Primary 

 spines smooth, cylindrical, with from three to six pairs of opposite spinules. The spinules are 

 stout, thorn-like, and directed distally. This species is the only Palaeozoic echinoid so far 

 known from Italy. 



Frequent in the calcareous schists, Carboniferous, Forca Pizzul, Carnic Alps. 



