Klem — Revision of the Palaeozoic Palae'echihnoidea. 19 



1875. PeriscJiodomus biserialis. Quenstedt, Petrefact. 

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



1876. PerificJiodomus biserialis. Keeping, Quart. Jourii. 



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

 1896. PeriscJiodomus 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. Tvpo columns 

 of small plates in each ambulacrum. 



Geological formation and locality : Lower Carboniferous, 

 Hook Head, Wexford, England. 



2. Pekischodomus iiartet Baily. 



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



5, p. 265, pi. 9. 

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



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

 1874. Archaeocidaris Harteiana. Baily, ,lourn. Geol. Soc. 



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

 1875. Quenstedt, Petrefact. Deutschl., vol. 



1, p. 379. 

 1^1 b. ArcJtaeocidaris Harteiana. Baily, Char. Brit. Foss., 



vol. 1, p. LXVIII. 



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

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

 174, taf. 1, fig. 7. 

 1892. Homotoeclms Harlii. Sollas, Scieut. 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 [)lates bear tubercles on the 

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

 sixth plates are [)lain. Ambulacra large, pores in two depres- 

 sions, with three pair of pores in each ambulacral depression. 

 One small tubercle on each ambulacral plate. 



Geological formation and locality : Yellow sandstone, 

 Donegal, Ireland. 



