IIO NEW YORK STATE MUSEUM 



Among the graptolites we have Dictyonema from the base of the 

 Ordovician to the Carboniferous, Desmograptus from the Ordovi- 

 cian to the Devonian. 



Among the Anthozoa in general, the number of persistent genera, 

 ranging through more than two periods, is remarkably large; the 

 number would be more than doubled if the genera living through 

 two periods only were to be added. 



Among the Crinoidea we find : 

 Silurian — Carboniferous . . ." . Cyathocrinus, Saccocrinus, Eutaxocrinus 



Triassic — Recent Isocrinus, Monachocrinus 



Cretaceous - Recent Rhizoerinus 



There are no persistent genera among the Cystoidea; among the 

 Blast oid ea, only Codaster extends from the Silurian into the Lower 

 Carboniferous. 



Among the Ophiuroidea all are short-lived ; among the Asteroidea 

 we find : 



Devonian (?) — Recent Astropecten 



Jurassic — Recent Oreaster 



Cretaceous — Recent Calliderma, Nymphaster, Comptonia 



In regard to the Ophiuroidea it is stated that in the lower, middle 

 and upper Jurassic are found brittle-stars closely allied to the 

 recent Ophiolepis, Ophiocten, Ophiura and Ophiomusium ; and 

 that it is possible that some of these are really congeneric with 

 recent species. 



The persistent Echinoidea are : 

 Silurian — Carboniferous .... Koninckoeidaris 

 Carboniferous — Jurassic .... Miocidaris 

 Triassic — Cretaceous Hemicidaris (subgenera) (Subgenus Hypo- 



diadema, Triassic-Cretaceous) 

 Triassic — Recent Cidaris (culminates in Jur.-Cret. ; artificial 



subgenera) 

 (Subgenus Rhabdoeidaris Jurassic-Recent; 



Leiocidaris Cretaceous-Recent) 



Jurassic — Recent Hemipedina, Centrechinus (Diadema auct.) 



Jurassic — Tertiary Cyphosoma, Nucleolites (Echincbrissus), 



Pseudodiadema, Cyphosoma 

 Cretaceous — Recent Linthia, Salenia, Echinus, Echinocyamus, 



Fibularia, Rhynchop3^gus (subgenus of 



Cassidulus), Palaeolampas 



The Vermes have furnished a few persistent genera of Poly- 

 chaeta or Marine Worms, namely : 



Ordovician — Recent Spirorbis 



Ordovician — Devonian Cornulites 



Ordovician — Carboniferous . . Ortonia 



Silurian — Recent Serpula (collective name for various forms) 



Jurassic — ■ Recent . . . : Terebella 



