422 THE CARBONIFEROUS PERIOD 



Ccelenterata. — Corals were abundant, and contributed largely 

 to the limestones; the genus Lithostrotion (PI. V, Fig. i), which 

 is peculiar to this period, plays a very prominent part. Lophophyl- 

 lum (PL VI, Fig. 14) is found in the Upper Carboniferous. 



Echinodermata make up an exceedingly important part of the 

 Carboniferous marine fauna. The Cystids have disappeared, but 

 the Blastoids have developed in great numbers and are highly 

 characteristic of the Carboniferous limestones. As the group is 

 entirely extinct and does not pass beyond the Carboniferous sys- 

 tem, its structure has much that is problematical about it. The 

 delicate, symmetrical body or calyx (PI. V, Fig. 2), which is 

 carried on a short stem, is composed of a small, definite number 

 of plates, and has five " pseudo-ambulacral " areas, which look 

 much like the ambulacra of a sea-urchin, but really are not at all 

 comparable to them. In exceptionally well preserved specimens 

 numbers of delicate pinnules are attached to these areas. The 

 most abundant genera are Penfre mites (V, 2) and Granatocrinns. 



All other Echinoderms of the Carboniferous seas were utterly in- 

 significant as compared with the Crinoids, which reach their cul- 

 mination of development in this period : more than 600 species 

 have been described from the Carboniferous limestones of North 

 America alone. Certain localities, such as Burlington (la.) and 

 Crawfordsville (Ind.), are famous for the vast numbers and exqui- 

 site preservation of their fossil sea-lilies. The crinoid remains 

 occur in such multitudes that in many places the limestones are 

 principally composed of them ; in such places they must have 

 covered the sea-bottom like miniature forests. All the Carbo- 

 niferous Crinoids, like those of the earlier periods, belong to the 



Explanation of Plate VI, p. 423. 1. Fusulina ventricosa, 2/1. (Meek.) 

 2. ^Esiocrinus magnificus, 1/2. 3. Spirifera camerata, 2/3. (Hall.) 4. Pro- 

 ductuspunctatus, 1/2. (White.) 5. Euomphalus subrugosus. (Meek.) 6. Pleuroto- 

 maria tabulata, 1/2. (White.) 7. Loxonema semicostata. (Meek.) 8. Aviculopecten 

 neglectus. (Meek.) 9. Allorisma subcuneatum, 1/2. (White.) 10. Sphenophyl- 

 lum Schlotheimi, 1/2. 11. Pecopteris orcopteridis, 1/2. 12. Lepidodendron cunea- 

 tum, fragment of bark, 1/2. (Rogers.) 13. Calamites Suckowi, 1/2. (Lesquereux.) 

 14. Lophophyllum proliferum. (Meek.) 



