134 CATALOGUE OF THE BLASTOIDEA. 



rocks. In Belgium the Upper Carboniferous Shale of Tournay has yielded Oropho- 

 crinns, Phamoschisma, and Mcsoblastus. As regards Germany, we have pointed out 

 above that we suspect Pentremites ovalis, Goldfuss, to be a Carboniferous and not a 

 Devonian species. 



In North America the series of rocks which we call Carboniferous Limestone are 

 by American geologists termed Subcarboniferous. According to Dana l , the series is 

 divided in the Interior Continental Basin into the following Groups, proceeding from 

 above downwards : — 



{Pentremital Limestone. 

 Upper Archimedes, or Kaskaskia Lime- 

 stone. 



e . T . ,-, f Warsaw Limestone. 



2. St. Louis Group < 



( Spergen Hill beds. 



3. Keokuk Group. 



4. Burlington Group. 



Choteau Limestone. 

 Goniatite Limestone. 



5. Kinderhook Group < 



Ten or possibly even twelve genera are known to exist, distributed throughout the 

 above groups, viz. — Pentremites, Mesoblastus, Granatocrinus, SchizoMastus, Crypto- 

 blastus, Codaster, Phamoschisma, Orophocrinus, Tricoelocrinus, Metablastus, and 

 perhaps Troostocrinus (T. \ Grosvenori), and Heteroblastus (H. 1 cornutus). Pentre- 

 mites is very largely represented, but we cannot give even an approximate idea of 

 the number of species, from the confused state of their synonymy. The earliest 

 representatives of the genus are two species in the Upper Burlington Limestone. 

 None are known from the Keokuk, and only two or three in the St. Louis Group ; 

 but there must be at least fifteen species in the Chester Limestone, after a liberal 

 allowance has been made for synonyms. 



Definite information is much needed with respect to the American species of 

 Granatocrinus. The typical species, G. Norwoodi, occurs low down in the series, in 

 the Burlington Group, together with its variety Jimbriatus. The species from the 

 St. Louis Group, which is generally known as Granatocrinus granulosus, Roem., sp., 

 may possibly belong to this genus, though we doubt it ; for we are by no means 

 clear that the deltoids are really perforated by the spiracles (Pi. VI. fig. 22). We 

 would say the same of most, if not all, of the other species which have been referred 

 to Granatocrinus. Many of them seem to us to belong to SchizoMastus. G. melo 

 is the type of our Cryptoblastus, while G. glaber is a Mesoblastus; and there may 

 perhaps he other American species which should be referred to one of these generic 



1 Muu. Geology, 3rd edit. j>. 294. 



