34 Trans. Acad. Sci. of St. Louis. 



observed in one and the same specimen — a fact sufficiently 

 recognized by the very authors who regard them as being 

 of importance for classification. All names ending in 

 " crinus " are omitted. 



I also wish to remark that this classification embraces only 

 our American species, although most of the European species, 

 I believe (judging from my small collection of European 

 specimens), will fit into one or another of these genera, with 

 the exception of aberrant forms, like some of our American 

 ones, of which it is still doubtful whether they should be 

 regarded as Blastoids or Cystoids, for the reception of which 

 a separate class should be established. This class may in- 

 clude all doubtful specimens and those insufficiently described 

 and doubtfully illustrated because of the fragmentary con- 

 dition of the material. 



CLASS BLASTOIDEAE. 

 A. Order Regulares. 



1. Family Pentremidae. 



1. Genus Pentremites, Say. 



2. Genus Cribroblastus. 



3. Genus Saccoblastus. 



4. Genus Clavaeblastus. 



5. Genus Mesoblastus, Etheridge fil. and Carpenter. 



6. Genus Cidaroblastus. 



7. Genus Globoblastus. 



8. Genus Codonites, Meek and Worthen. 



2.;Family Codasteridae. 



1. Genus Codaster, Maccoy. 



