CARBONIFEROUS AGE. 297 



profuse for the amount of land, although the circumstances were less 

 favorable for its growth and accumulation in marshes, — the essential 

 prerequisite for the formation of large beds of coal. 



In the Subcarboniferous of Pennsylvania occur, according to Lesquereux, Cyclopteris 

 obtusa Lsqx (also found in the Catskill group of the Upper Devonian), & Bockschiana 

 Gbpp., remains of Lepidodendra and Stiymaria mhiuta Lsqx. ; also, in Illinois, the 

 Tree-fern Meyaphytum protuberans Lsqx., Caulopteris Worthenii Lsqx., Lepidoden- 

 dron costatum Lsqx., L. turbinatum Lsqx., L. obscurum Lsqx., L. Veltheimianum 

 Sternb., L. Worthianum Lsqx., Stiymaria anabathra Corda, S. minor Gbpp., S. umbo- 

 iiata Lsqx., and others; Calamites Suckowii Brngt., Knorria imbricata Sternb., all 

 from the Chester group. 



In the Chester group sandstones of Indiana, according to Collett, occur Stiymaria, 

 Lepidodendvon aculeatum, L. diploteyioides Lsqx., L. forulatum Lsqx., Lepidostvobus, 

 Knorria, Hymenophyllites Clarlcii Lsqx., Cordaites borassifolia, Neuroptevis dilatata 

 Lsqx., N. rarinervis Lsqx., Alethopteris Owenii Lsqx., Calliptevis Sullivantii Lsqx., etc. 

 One specimen of Lepidodendrcm had portions of the leaves attached to the stem, and 

 twelve to fourteen inches long, though only from one-eighth to one-fourth of an inch in 

 width. 



In the Subcarboniferous of Nova Scotia and New Brunswick, Dawson has made 

 out the following species: Ferns, Cyclopteris Acadica Dn., and another species sup- 

 posed to be a Hymenophyllites ; Lycopods: Lepidodendvon corruyatum Dn., L. Stevn- 

 ■beryii Hmgt., L. tetrayonum Sternb., L. aculeatum Sternb., Lycopodites plumida Dn.; 

 also Stiymaria Jicoides Brngt., Cordaites borassifolia Ung. 



Of the above, the Stiymarim, Calamites, Cordaites, and Lepidodendvon Worthianum 

 occur higher in the series, the Calamites and Cordaites continuing even into the Upper 

 Coal-measures. 



2. Animals. 



The animal life was remarkable for the great profusion and diver- 

 sity of Crinoids, — or Sea-lilies, as they are sometimes called. Some 

 of the Crinoids — mutilated of their rays or arms, as is usual with 

 these fragile species, except when buried in shales — are represented 

 in Figs. 573-582. The period might well be called the Crinoidal 

 period in geological history. Among the kinds, the Pentremites (Figs. 

 580-582) are perhaps the most characteristic. Instead of having a 

 circle of arms, like most Crinoids, the summit is closed up, so as to 

 look like a bud (whence the name Blastids,- applied to the family, from 

 the Greek ^'Aaord?, a bud) ; and the delicate jointed tentacles are 

 arranged in vertical lines along the pseudo-ambulacral areas. 



There were also other Echinoderms, related to the modern Echinus, 

 but peculiar in the large number of vertical series of plates of which 

 the shell consists. One species is represented in Fig. 58(3, but one 

 half the natural size. The vertical series of plates in the ambulacral 

 series, which are indistinct in this figure, are shown, enlarged, from 

 another species, in Fig. 587 b. Fig. 587 represents a top view, and 

 587 a a portion of the lateral, of still another of these ancient Echi- 

 noids. A true Polyp-Coral, eminently characteristic of the period, is 

 the Lithostrotion Ganadense (Figs. 588, a). It is a columnar coral, 

 having a conical elevation at the bottom of each of the cells, and grows 

 often to a very large size. 



