INCERTAE SEDIS. 453 



Palaeocidaris exilis Eichwald. 



Text-fig. 254. 



Palaeocidaris crilis Eichwald, 1854, p. 114. Plate 2, fig. 14. 

 Bothriocidaris crilis Eichwald, 1860, p. 656. 



A small unrecognizable mass. In general, it is spheroidal in form, and has numerous smal 

 elevations which Eichwald considered to be tubercles. 



Pentamerous Limestone, Silurian, of Talkhof, Russia. 



Palaeodiscus gothicus Wyville Thomson. 



Palacodiscus gothicus Wyville Thomson, 1861, p. 118, Plate 4, fig. 8; Lambert 

 andThiery, 1910, p. 117. 



This species is unrecognizable. 



Lower Ludlow Flags, Silurian, Leintwardine, Shropshire, England. 254 



Text-fig. 254. — Palaeoci- 

 daris exilis Eichwald. Holo- 

 type. Natural size and en- 

 larged. After Eichwald, 1854, 

 Plate 2, fig. 14. 



Palaeospatangus skiptoni Harte. 



Palaeospatangus skiptotii Harte, 1869, pp. 135, 136. 



Described as spatangoid in shape, but no recognizable description 

 is given. All data are doubtful, but Harte thought that the specimen came from the Lower 

 Carboniferous Sandstone of Scotland. 



Perischodomus magnus Tornquist. 



Perischodomus magnm Tornquist, 1893, p. 103; Klem, 1904, p. 20. 



Described from a single interambulacral plate which bears a primary and secondary- 

 tubercles. The status of the species is doubtful as well as its generic reference. 

 Lower Carboniferous, Upper Alsace, Germany. 



Protoechinus T. Austin. 



Protoechinus T. Austin, 1860, p. 446; Loven, 1874, p. 42; Jackson, 1896, p. 235; Klem, 1904, p. 75. 

 Palaeechinus (pars) Duncan, 1889a, p. 13. 

 Mcloncchirms (pars) Lambert and Thiery, 1910, p. 120. 



Ambulacra with two columns of plates, and passing toward the wider portion of the area 

 with intercalated plates added, producing four columns. There is a pore-pair in each plate. 

 The interambulacrum is fragmentarily known, and other parts of the test are unknown. 



Type species, P. anceps Austin, from the Lower Carboniferous of Ireland. 



