32 Trans. Acad. Sci. of St. Louis. 



General form elliptical. Interambulacra composed of five 

 columns of plates, regularly marked with numerous tubercles. 

 Ambulacra prominent, convex, with two rows of pores on 

 each side. One lateral interambulacral plate is as wide as 

 seven ambulacra! plates. 



Geological formation and locality : Carboniferous Lime- 

 stone, Betty ville, Limerick Co., Ireland. 



2. Palaechinus gigas M'Coy. 



1844. Palaechinus gigas. M'Coy, Foss. of Ireland, p. 172, 



pi. 24, fig. 4. 

 1850. Palaechinus gigas. D'Orbigny, Prodrome, vol. 1, p. 



154. 

 1858. Palaechinus gigas. Desor, Syn., p. 158. 

 1862. Palaechinus gigas. Dujardin et Hupe, Echinodermes, 



p. 463. 

 1874. Palaechinus gigas. Baily, Journ. Roy. Geol. Soc. 



Ireland, ser. 2, vol. 4, pt. 1, p. 41, pi. 3. 



1874. Palaechinus gigas. Love'n. Kongl. Svens. Vetens. 

 Akad. Handl., Bd. 11, No. 7, p. 41. 



1875. Palaechinus gigas. Quenstedt, Petref. Deutschl., p. 

 380, tab. 75, fig. 40. 



1876. Palaechinus gigas. Keeping, Quart. Journ. Geol. 

 Soc. Lond., vol. 32, pt. 1, p. 38, pi. 3, figs. 12, 13. 



1889. Palaechinus gigas. Duncan, Ann. Mag. Nat. Hist., 



ser. 6, vol. 3, p. 198, fig. 1. 

 1896. Palaechinus gigas. Jackson, Bull. Geol. Soc. Amer., 



vol. 7, p. 204, pi. 7, figs. 38, 39. 

 1896. Palaechinus gigas. Julien, Terr. Carb. France Cen- 



trale, p. 130. 

 General form orbicular, depressed. Interambulacra com- 

 posed of six columns of plates. Pores in four rows on each 

 side of the ambulacrum. One adarabulacrum plate is as wide 

 as seven ambulacral plates. Tubercles large, each surrounded 

 by a ring. Space between the tubercles smooth. 



Geological formation and locality : Carboniferous Lime- 

 stone, Hook Head, Fethard, Rahan's Bay, Dunkineely, Great 

 Britain; Re'gny, France. 



