DESCRIPTIONS OF THE SPE0IE8. 171 



while in P. clavaia, var. Schultzei, there arc six folds, which are freely pendent into 

 the body-cavity (PI. A", figs. 3, 5), and in /'. Paillettei there are eight (PI. XVII. fig. 

 11), the uppermost of winch seem to he cut out of the radials as in I'lm noschisma 

 and Orophocrinus (PI. XVII. figs. 13-10). 

 Species. The following species arc, we believe, referable to Pentremitidea : — 



Pentremites acutangulus, Schultze. Middle Devonian; Eifel. 



J', ntremitidea Americana, Harris. Upper(or Middle !) Devonian; North Michigan. 



Pentremitidea angulata, E. & C. Lower Devonian; Asturias, Spain. 



Pentremites clavatus, Schultze. Middle Devonian ; Eifel. 



Pentatrematites Eifelensis, Roemer. Middle Devonian; Eifel. 



Pentremites Fraiponti, Dewalque. Lower Devonian; Belgium. 



Pentremitidea (lilbcrtsoni, sp. nov. Lower Devonian; Leon, Spain. 



\ Pentatrematites gracilis, Steininger. Middle Devonian; Eifel. 



1 Pentremites U da, Hall. Upper (or Middle 1) Devonian ; West New York State. 



Pentremitidea Lusitanica, E. & C. Lower Devonian ; Asturias, Spain. 



Pentremitidea Malladai, E. & C. Lower Devonian; Leon, Spain. 



\ Pentatrematites planus, G. & F. Sandberger. Middle Devonian; Nassau. 



Pentremitidea Poemeri, sp. nov. Middle Devonian; Eifel. 



Pentremitidea similis, E. & C. Middle Devonian ; Eifel. 



Pentremitidea Wachsmuthi, sp. nov. Lower Devonian ; Leon, Spain. 



Pentremitidea "iWhidiornei, sp. nov. Middle Devonian; South Devon. 

 Distribution. Pentremitidea is limited to rocks of the Devonian Period, just 

 as Pentremites is to the Carboniferous Limestone, and it may fairly be called the 

 characteristic Devonian genus of Blastoids. For, unlike Pentremites (with the 

 possible exception of P. oralis, Goldf), it occurs on both sides of the Atlantic, being 

 well represented in Germany and Spain, and by single species in Belgium and 

 Britain. It is limited in America to the Hamilton Group of the Upper (or 

 Middle V) Devonian, which contains at least two, and perhaps six, species. The only 

 British species known occurs in the Plymouth Limestone of Middle Devonian age ; 

 and if the Pentatrematites planus which has been described by G. & F. Sandberger 

 from the " Stringocephalenkalk " of Nassau be a Pentremitidea, then the genus 

 would also occur in the Middle Devonian of that part of Germany, which is limited 

 by Barrois to this horizon. According to most authors, however, the limestones of 

 the Eifel district which contain six species of Pentremitidea, are of Middle Devonian 

 age. But in any case there are several species from the Lower Devonian. Apart 

 from the six in the " Eifeler Ivalk," we know of seven from the Lower Devonian of 

 Spain, one of which (P. clavata) is common to the Eifel beds. According to 

 Barrois 1 these are at a slightly higher horizon than the " Calcaire dArnao " of the 

 Asturias ; and one of the species in this bed (P. Paillettei) is also found both in 

 1 Mem. Sue. Geol. du Nord, 1S82, tome ii. Mem. 1, p. 518. 



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