Klem — Revision of the Palaeozoic Palaeechihnoidea. 19 



1875. Perischodomus biserialis. Quenstedt, Petrefact. 

 Deutschl., bd. 3, abth. 1, p. 374, tab. 75, fig. 13. 



1876. Perischodomus biserialis. Keeping, Quart. Journ. 



Geol. Soc, vol 32, pt. 1, p. 36, pi. 3, figs. 1-5. 

 1896. Perischodomus biserialis. Jackson, Bull. Geol. Soc. 

 Amer., vol. 7, p. 226. 

 Interambulacra consist of five columns of irregular, very 

 finely granulated plates. Adambulacral plates bear small, 

 mammillated, perforated, primary tubercles. Two columns 

 of small plates in each ambulacrum. 



Geological formation and locality : Lower Carboniferous, 

 Hook Head, Wexford, England. 



2. Perischodomus hartei Baily. 



1864. Harte, Dub. Quart. Journ. Sci., vol. 



5, p. 265, pi. 9. 

 1864. Harte, Journ. Koy. Geol. Soc. Ireland, 



ser. 2, vol. 1, pt. 1, p. 67, pi. 5. 



1874. Arcliaeocidaris Harteiana. Baily, Journ. Geol. Soc. 

 Ireland, n. s. vol. 4, pt. 1, p. 42, pi. 4, figs. a-c. 



1875. Quenstedt, Petrefact. Deutschl., vol. 



1, p. 379. 



1875. Arcliaeocidaris Harteiana. Baily, Char. Brit. Foss., 

 vol. 1, p. LXVIII. 



1881. Perischocidaris Hartei. Neumayr, Sitzb. K. Akad. 

 Wiss. Wien, Math.-Naturw. CI., Bd. 84, Abth. 1, p. 

 174, taf. 1, fi£. 7. 



* ' CD 



1892. Homotoechus Hariii. Sollas, Scient. Proc. Roy. Dub. 

 Soc, n. s. vol. 7, pt. 3, p. 153. 



Genital plates have each a large perforated tubercle, sur- 

 rounded by a depressed ring, which is further surrounded by 

 sixteen pores. Adambulacral plates bear tubercles on the 

 first, second, fourth and seventh, while the third, fifth and 

 sixth plates are plain. Ambulacra large, pores in two depres- 

 sions, with three pair of pores in each ambulacra] depression. 

 One small tubercle on each ambulacra! plate. 



Geological formation and locality: Yellow sandstone, 

 Donegal, Ireland. 



