274 



PALEOZOIC TIME DEVONIAN AGE. 



Fig. 452. 



(c. ) Echinoderms. — There are many species of Crinoids, and the large, 

 smooth stems of some of them are half an inch to an inch in diameter. 

 The species of most interest are the Nucleocrini (also 

 called Olicanitcs); they are representatives of the Pen- 

 tremite family, — a group which had its first species in 

 the Chazy, the early part of the Trenton period, in the 

 Lower Silurian, but which from that time appears to have 

 been extinct until the Corniferous period in the Devo- 

 nian. In the Subcarboniferous period it was very com- 

 mon. The species of this period are ovoidal, or like 

 an olive in shape, and have ambulacral areas closely 

 like those of the true (pentagonal) Pentremites (figs. 

 531, 532). Fig. 452 is the Nuclebcrimts Verneuili. (The 

 name Nucleoerinus of Conrad antedates Olivanites of Troost, 

 as well as Elseacrhms of Roemer.) 



2. Mollusks — («.) Brachiopods. — Figs. 453 and 454, Spirifer acuminates 

 Con. (S. cultrijwjatus Roemer), from New York and the West. Fig. 455, Spirifer 



Figs. 453-455. 



55 



Nucleoerinus Ver- 

 neuili. 



Erachiopods. — Figs. 453, 454, Spirifer acuminatus ; 455, Sp. gregarins. 



gregarius, very common in Indiana and Kentucky, at the Falls of the Ohio, and 

 at Middleton, Canada (Billings). Also, Pentamerus aratus, Chonetes hemisjihe- 



Figs. 456, 457. 



Conchifers.— Fig. 456, Lucina? proavia; 457, Con 



ocardiuni triiiouale. 



rica, Afnjpa reticularis, A. imprMa, Strielclandia elongata (Billings), formerly 

 Pentamerus elongates Vanuxem ; also a Calceola near C. sandaUna (fig. 2:51), 



