132 CATALOGUE OF THE BLASTOLDEA. 



name of Pentremites Roemeri, which was subsequently changed to Granatocrinus 

 Missouriensis 1 . Mr. S. A. Miller tells us, however, that this species really belongs 

 to the middle or upper part of the Subcarboniferous ; and we must therefore leave 

 the existence of Schizohlastus as a Devonian genus in some doubt. 



The same remarks apply to Granatocrinus as represented by G. Roemeri, Shumard 8 ; 

 though Hall 3 has described three species of Pentremites from the Hamilton Group, 

 any one of which may really belong to this genus, viz. P. calyce, P. lycorias, and 

 P. Whitei. But it is equally possible that they should be referred to Mesoblastus or 

 to Pentremitidea. An unquestionable example of tire latter genus has, however, 

 been recently described by Barris 4 from the Hamilton Group of Michigan; and 

 Hall's Pentremites leda (PI. V. figs. 12-14) is probably an aberrant species of the 

 same generic type. 



We know of no Troostoblastidee of Devonian age in America, though the family 

 is represented by single species in the Devonian of Britain, France, and Spain ; but 

 we cannot refer them for certain to Metablastus or to Troostocrinus. In our notes 5 

 on the latter genus, published a few years ago, we included Pentremites subtruncatus, 

 Hall, from the Hamilton Group of Iowa, as a Troostocrinus. We were probably in 

 error in this reference, for this species now appears to us to be more nearly allied to 

 Codaster or Phcenoschisma. We have no certain knowledge that the latter genus 

 occurs at all in the American Devonian, though we have seen some undescribed 

 Carboniferous species ; while Codaster is abundant both in the Lower and in the 

 Upper Devonian, though it is only known as a Carboniferous genus in Europe. 



Taking the Blastoids of the Devonian system as a whole, we find that they present 

 several points of interest. 



(1) The number of genera was largely increased at the close of the Silurian period, 

 all the families being represented in the Devonian. 



(2) The genus Pentremites, which is the type of the class, has, however, not yet 

 made its appearance. 



(3) The Silurian Troostoblastidre disappear in the American Devonian Series, but 

 are well represented in Europe. 



(4) The appearance of Pentremitidea on both sides of the Atlantic, though it 

 attains a much greater development in the European area, and is not known in 

 America below the Upper Devonian. 



1 Tram. St. Louis Acad. Sci. 1865, vol. ii. no. 2, p. 375. In our list of species of Schizohlastus we called 

 this specif s /' »lrrmil< s. We should have written Granatocrinus, the name eventually given to it by Shuinard 

 (see Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 247). 



As restricted in Trans. St. Louis Acad. Sci. 1805, vol. ii. no. 2, p. 376. 



■■ Fifteenth Annual Report New York State Cab. Nat. Hist, 1862, pp. 150 & 151. 



' Proc. Davenport Acad. Nat. Sci. 1885, vol. iv. p. 'J3, pi. i. fig. 4. 



5 Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 249. 



