HYATTECHINUS. 291 



*Lepidocentrus eifelianus Muller. 

 Plate 20, fig. 14. 



Lepidocentrus eifelianus Muller, 1857, p. 258, Plate 3, figs. 1-8; Schultze, 1866, p. 123, Plate 13, figs. 2-2c; 

 Loven, 1874, p. 40; Quenstedt, 1875, p. 374, Plate 75, figs. 14-17; Jackson, 1896, p. 225; Klein, 

 1904, p. 16; Lambert and Thie"ry, 1910, p. 122. 



This species, the type of the genus, is known only from isolated interambulacral plates 

 and spines. The plates are thinner and more rounded in form than those of L. mulleri, but 

 with similar surface ornaments. The spines are similar to those of mulleri. 



Devonian, Nohn, and Rommersheim, from the Schultze Collection, Museum of Compara- 

 tive Zoology 3,061, 3,068, 3,069; Berlin Museum fur Naturkunde, doubtless the types. 



TORNQUISTELLUS Berg. 



Leptechinus Tornquist, 1897, p. 785 (non Gauthier, Echinides fossiles de la Tunisie, 1869). 

 Tornquistellus Berg, 1899, p. 77. 



Known only from interambulacral plates, which are small, thin, imbricating, with sparsely 

 distributed secondary tubercles. While the material is so meager, its affinities are distinctly 

 with Lepidocentrus, from which it differs in having secondary tubercles only. 



Type species T. gracilis. 



Tornquistellus gracilis (Tornquist). 

 Plate 20, fig. 15. 



Leptechinus gracilis Tornquist, 1897, p. 785, Plate 20, fig. 5. 

 Tornquistellus [gracilis] Berg, 1899, p. 77. 

 Perischodomus gracilis Lambert and Thiery, 1910, p. 122. 



Known only from isolated interambulacral plates, which are thin, flat, wider than high, 

 slightly angular, but very nearly rhombic in outline. The type specimen measures 8 mm. 

 in width and 5 to 6 mm. in height. The surface is ornamented with about 20 small tubercles. 

 This species has characters which would not fit into any other genus, so that, although so little 

 is known of it, Tornquist was quite justified in establishing a new genus for its reception. 



Lower Carboniferous, rare at Hunsriicken, Germany; holotype, in the Strassburg Museum 



Collection. 



HYATTECHINUS gen. nov. 



Test spheroidal or flattened; through the ambitus nearly circular; pentagonal or elongate 

 through an axis passing through an ambulacrum and opposite interambulacrum, which I take 

 to be the axis III, 5. Ambulacra wide, petaloid ventrally, narrow dorsally. Two columns 

 of plates in each ambulacral area, plates relatively high and wide ventrally, lower and narrower 



